JavaScript技巧精粹

发布时间：2025-09-30 21:02

阅读Eloquent JavaScript提高JavaScript技能：https://eloquentjavascript.net/ #生活技巧# #工作学习技巧# #编程学习资源#

var colorText = "red,blue,green,yellow";

var one = colorText.split(",");

var two = colorText.split(",", 2);

var thr = colorText.split(/[^\,]+/)

console.log(one);

console.log(two);

console.log(thr);

function htmlEscape(text) {

return text.replace(/[<>"&]/g, function(match, pos, originalText) {

switch(match) {

case "<":

return "<";

case ">":

return ">";

case "&":

return "&";

case "\"":

return """;

}

});

}

console.log(htmlEscape("<p class = \"greeting\">Hello World !</p>"));

var text = "cat, bat, sat, fat";

result = text.replace(/(.at)/g, "word ($1)");//匹配第一個字符串捕獲組

console.log(result)

var text = "cat, bat, sat, fat";

var result = text.replace("at", "ond");

console.log(result);

result = text.replace(/at/g, "Rui");

console.log(result);

var text = "cat, bat, sat, fat"

var pos = text.search(/at/);

console.log(pos);

var text = "cat , bat , sat , fat";

var pattern = /.at/;

//與pattern.exec(text)

var matches = text.match(pattern);

console.log(matches.index);

console.log(matches[0]);

console.log(pattern.lastIndex);

var sV = "hello world";

console.log(sV.toLocaleUpperCase());

console.log(sV.toUpperCase());

console.log(sV.toLocaleLowerCase());

console.log(sV.toLowerCase());

var sV = " Hello World ";

var one = sV.trim();

console.log(one);

var sV = "Lorem ipsum dolor sit amet, consectetur adipisicing elit";

var positions = new Array();

var pos = sV.indexOf("e");

while(pos > -1) {

positions.push(pos);

pos = sV.indexOf("e", pos + 1);

}

console.log(positions);

var sV = "Hello World"

console.log(sV.indexOf("o"));

console.log(sV.lastIndexOf("o"));

console.log(sV.indexOf("o",6));

console.log(sV.lastIndexOf("o",6));

var sV = "Hello World";

console.log(sV.slice(-3));//11-3 =8

console.log(sV.substring(-3));//=0

console.log(sV.substr(-3));

console.log(sV.slice(3,-4));

console.log(sV.substring(3,-4));//等於3，0，小的排前，所以0，3

console.log(sV.substr(3,-4));

var stringValue = "hello World"

console.log(stringValue.charAt(1));

console.log(stringValue.charCodeAt(1))

console.log(stringValue[0])

var stringValue = "hello ";

var result = stringValue.concat("World" + " !");

console.log(result);

var stringValue = "Hello World";

console.log(stringValue.slice(3));

console.log(stringValue.substring(3));

console.log(stringValue.substr(3));

console.log(stringValue.slice(3,8));

console.log(stringValue.substring(3,8));

console.log(stringValue.substr(2,7));

var stringObject = new String("hello world");

console.log(stringObject)

var stringValue = "Hello World";

console.log(stringValue.length);

var numberObject = new Number(10); 創建number對象的實例

var numberValue = 10;

console.log(typeof numberObject);

console.log(typeof numberValue);

console.log(numberObject instanceof Number);

console.log(numberValue instanceof Number);

var number = new Number(10);

//console.log(number)

var num = 10;

console.log(num.toFixed(2));

var num = 10.005;

console.log(num.toFixed(2));

var num = 10;

console.log(num.toExponential(1));

var num = 123.4567890;

console.log(num.toPrecision(5));

console.log(num.toPrecision(2));

var falseObject = new Boolean(false);

var result = falseObject && true;

console.log(falseObject instanceof Boolean);

console.log(result);

var falseValue = false;

result = falseValue && true;

console.log(falseValue instanceof Boolean)

console.log(result);

var booleanObject = new Boolean(true);

console.log(typeof booleanObeject)

var value = "25"

var number = Number(value);//轉型函數

console.log(typeof number);number

var obj = new Number(value);

console.log(typeof obj);//對象

var obj = new Object("some text");

console.log(obj instanceof String);

//基本包裝類型、執行瞬間刪除

var s1 = "some text";

s1.color = "yellow";

console.log(s1.color);

var s1 = "some text";

var s2 = s1.substring(2);

console.log(s2)

//過程，後臺處理~

var s1 = new String("some text");

var s2 = s1.substring(2);

s1 = null;

console.log(s2);

color = "red";

var r = {color:"yellow"};

function sayColor() {

console.log(this.color);

}

var one = sayColor.bind(r);//創建一個one函數實例，把其 this 通過bind 綁定到r對象。

one()

window.color = "yellow";

var r = {color: "blue"};

function sayColor() {

console.log(this.color);

}

//更下面等價

sayColor.call(r)

//更下面等價

r.sayColor = sayColor;

r.sayColor();

//call 方法

function sum(num1, num2) {

return num1 + num2;

}

function callSum(num1, num2) {

return sum.call(this, num1, num2);

}

console.log(callSum(10, 10))

//apply 方法

function sum(num1, num2) {

return num1 + num2;

}

function callSum1(num1, num2) {

return sum.apply(this, arguments);//apply 2參數，1是其運行函數的作用域，2是參數數組。

}

function callSum2(num1, num2) {

return sum.apply(this, [num1, num2]);

}

console.log(callSum1(10, 10));

console.log(callSum2(10, 10))

//函數的 length 屬性

function sayName(name) {

console.log(name)

}

function sum(num1, num2) {

return num1 + num2;

}

function sayHi() {

console.log("hi");

}

console.log(sayName.length);

console.log(sum.length);

console.log(sayHi.length);

//caller 可記住 “開燈的人”

function outer() {

inner();

}

function inner() {

//alert(inner.caller);

console.log(arguments.callee.caller);

}

outer();

//this 對象

window.color = "red";

var o = {color: "blue"};

function sayColor() {

console.log(this.color);

}

o.sayColor = sayColor;

o.sayColor()

function factorial(num) {

if (num <= 1) {

return 1;

} else {

return num * arguments.callee(num-1);

}

console.log(factorial(2));

//函數中返回另一個函數

function createComparionFunction(onename) {

return function(object1, object2) {

var value1 = object1[onename];

var value2 = object2[onename];

if (value1 < value2) {

return -1;

} else if(value1 > value2) {

return 1;

} else {

return 0;

}

var data = [{name:"Rui",age:28},{name:"Hong",age:20}]

data.sort(createComparionFunction("name"));

console.log(data[0].name);

data.sort(createComparionFunction("age"));

console.log(data[0].age);

//函數中運用函數！

function Rui(someFunction, someArgument) {

return someFunction(someArgument);

}

function add10(num) {

return num + 10;

}

var resule = Rui(add10, 10);

console.log(resule)

function getGreeting(name) {

return "hello, " + name;

}

var whoName = Rui(getGreeting, 'Papa');

console.log(whoName);

//無函數聲明，不可能比先運行，

console.log(rui(0));

var rui = function(num){

return num;

}

//可執行。

alert(rui(1));

function rui(num) {

return num

}

function add(num) {

return num + 100;

}

function add(num) {

return num + 200;

}

console.log(add(200));

var rui = function(num) {

return num + 1;

}

rui = function(num) {

return num + 2;

}

console.log(rui(0))

var text = "this has been a short summer.";

var pattern = /(..)or(.)/g;

if (pattern.test(text)) {

console.log(RegExp.$1);

console.log(RegExp.$2);

console.log(RegExp.$3);

console.log(RegExp.$4);

console.log(RegExp.$5);

console.log(RegExp.$6);

console.log(RegExp.$7);

console.log(RegExp.$8);

console.log(RegExp.$9);

}

var text = "this has been a short summer"

var pattern = /(.)hort/g;

if (pattern.test(text)) {

console.log(RegExp.$_);

console.log(RegExp["$`"]);

console.log(RegExp["$'"]);

console.log(RegExp["$&"]);

console.log(RegExp["$+"]);

console.log(RegExp["$*"]);

}

//RegExp 構造函數屬性！

var text = "this has been a short summer"

var pattern = /(.)hort/g;

if (pattern.test(text)) {

console.log(RegExp.input);

console.log(RegExp.leftContext);

console.log(RegExp.rightContext);

console.log(RegExp.lastMatch);

console.log(RegExp.lastParen);

console.log(RegExp.multiline)

}

var text = new RegExp("\\[bc\\]at","gi");

one = text.toString();

one = text.toLocaleString()

one = text.valueOf

console.log(one)

var text = "000-00-0000"

var one = /\d{3}-\d{2}-\d{4}/;

if (one.test(text)){

console.log("U Can")

}

console.log(one);

//全局和局部exec()的區別。。局部只會返回第一位

var text = "cat,bat,sat,fat";

var one = /.at/;

var go = one.exec(text);//"cat"

goo = go.index;//"0"

goo = go[0]//"cat"

goo = one.lastIndex;//"0"

//console.log(goo);

var two = /.at/g;//at結尾的3位數

var texttwo = two.exec(text);

go = texttwo.index;

go = texttwo[0];

go = two.lastIndex;

go = texttwo = two.exec(text);

go = texttwo.index;

go = texttwo[0];

go = two.lastIndex;

console.log(go);

var text = "mom and dad and baby";

var find = /mom( and dad (and baby)?)?/gi;

var go = find.exec(text)

goo = go.index

goo = go.input

goo = go[0]

goo = go[1]

goo = go[2]

goo = go[3]

console.log(goo);

var one = /\[bc\]at/i;

go = one.global;

go = one.ignoreCase;

go = one.lastIndex;

go = one.multiline;

go = one.source;//"\[bc\]at"

console.log(go);

var two = new RegExp("\\[bc\\]at","i");

goo = two.global;

goo = two.ignoreCase;

goo = two.lastIndex;

goo = two.multiline;

goo = two.source;

console.log(goo);

//正則表達式

var one = /[bc]at/i;//匹配第一個 bat和cat，不區分大小

var one = /\[bc\]/i;//匹配第一個【bat】或【cat】，不區分大小

var one = /.at/i;//匹配所有以"at"結尾的3個字符的組合，不區分大小

var one = /\.at/gi; //匹配所有".at"，不區分大小

var one = /[bc]at/i;//匹配第一個‘bat’或‘cat’ 不區分大小

var two = new RegExp("[bc]at","i")//與one樓上相同的，使用構造函數創建

console.log(two)

var re = null,

for (i = 0; i < 10; i++) {

re = /cat/g;

re.test("catastrophe");

}

console.log(one)

時間

var times = new Date();

var a = times;

time = times.toDateString()

time = times.toTimeString()

time = times.toLocaleString()

time = times.toLocaleDateString()

time = times.toLocaleTimeString()

time = times.toUTCString()

time = times.toGMTString()

time = times.getTime()

//time = a.setTime()

time = a.getFullYear()

time = a.getUTCFullYear()

//time = a.setFullYear();

time = a.getMonth()

time = a.getUTCMonth()

time = a.getTime()

console.log(time)

var a = new Date(Date.parse("5/19/2017"))

console.log(a)

//迭代！

var numbers = [1,2,3,4,5,4,3,2,1];

var everyResult = numbers.every(function(item,index,array){

return (item > 2);

})

console.log(everyResult);

var someResult = numbers.some(function(item,index,array){

return (item > 2);

})

console.log(someResult);

var filterResult = numbers.filter(function(item,index,array){

return (item > 2);

})

console.log(filterResult);

var mapResult = numbers.map(function(item,index,array){

return item * 2;

})

console.log(mapResult

)

var reduceResult = numbers.reduce(function(prev,cur,index,array){

return prev + cur;

})

console.log(reduceResult)

var number = [1,10,2,5];

var reduceRight = number.reduceRight(function(prev,cur,index,array){

return prev + cur;

})

console.log(reduceRight)

var person = {name: "Nicholas"};

var people = [{name: "Nicholas"}];

var morePeople = [person];

console.log(people.indexOf(person));

console.log(morePeople.indexOf(person))

var number = [1,2,3,4,5,4,3,2,1];

console.log(number.indexOf(4))

console.log(number.lastIndexOf(4))

console.log(number.indexOf(4,4));

console.log(number.lastIndexOf(4,4))

//splice() 連接~

var color = ["yellow","blue","red"];//新建數組

var removed = color.splice(0,1);//刪除 0 下標位置的項，數量1

removed = color.splice(1,0,["value1"],["value2"]);

removed = color.splice(2,1,["value3"],["value4"]);

console.log(removed);//返回的數組中只包含一項；

console.log(color)

//slice() 切割

var color = ["red","green","blue","yellow","black"]

var colors = color.slice(1);

var colors2 = color.slice(2,4);

console.log(colors)

console.log(colors2)

var colors = ["red",'green','yellow'];

var colors2 = colors.concat("black",["blue",true]);

var color = colors.concat();

console.log(color)

//比較函數

function compare(value1, value2) {

if (value1 < value2) {

return -1;

}else if(value1 > value2) {

return 1;

}else {

return 0;

}

//更簡單的比較函數

function compare1(value1, value2) {

return value2 - value1;

}

var values = [0, 1, 5, 10, 15, 20];

values.sort(compare1);

console.log(values);

//隊列方法 shift()

var one = [];

one.push("yellow","red")

one[2] = "black"

one = one.shift();

console.log(one)

var colors = new Array();

var count = colors.unshift("yellow","red");

count = colors.unshift("black");

var item = colors.pop();

console.log(item)

console.log(count)

console.log(colors)

//這些數組可以看成棧！

var colors = new Array();

var count = colors.push("red","blue")

count = colors.push("yellow")

var item = colors.pop();

console.log(colors.length)

console.log(colors)

var p1 = {

toLocaleString : function() {

return "one";

toLocaleString : function() {

return "two";

}

};

var p2 = {

toString : function() {

return "one";

toString : function() {

return "two";

}

};

var p = [p1,p2];

alert (p)

alert (p.toString());

alert (p.toLocaleString())

console.log(p)

function displayInfo(args) {

var output = "";

if (typeof args.name == "string"){

output += "Name: " + args.name + "\n";

}

if (typeof args.age == "number") {

output += "age: " + args.age + "\n";

}

alert(output);

}

displayInfo({

name: "nicholas",

age: 18

});

displayInfo ({

name: "Greg"

});

var o = {x:"one", y:"two"};

a = delete o.x;

a = typeof o.x;

a = delete o.x;

a = delete o;

a = delete 1;

a = this.x = 1;

a = delete x;

a = x

console.log(a)

var geval = eval;//使用別名調用 eval 將是全局 eval

var x = "global", y = "global";

function f() {

var x = "local";

eval("x += 'changed';");

return x;

}

console.log(f())

function g() {

var y = "local";

geval("y += 'changed';");//調用改變了全局變量的值

return y;

}

console.log(g());

a = eval("3+2")

console.log(a)

//屬性訪問表達式

var o = {x:1, y:{z:3}};

var a = [o,4,[5,6]];

b = o.x

b = o.y.z

b = o[0]

b = o["x"]

b = a[1];

b = a["1"];

b = a[1];

b = o[0]

b = a[2]["1"]

b = a[2][0]

b = a[0].x

console.log(b);

function createperson(name) {

var localperson = new Object();

localperson.name = name;

return localperson;

}

var globalPerson = createperson("Nicholas");

//手工解除 globalPerson的引用；

globalPerson = null;

console.log(globalPerson)

var element = document.getElementById("some_element");

var myObject = new Object();

myObject.element = element;

element.someObject = myObject;

//結果會返回color，搜索過程從作用域的前端開始，

//向上逐級查詢給定名字匹配的標識符。

var color = "blue";

function getColor() {

return color;

}

console.log(getColor());

// JS 中 if 語句中的變量聲明會將變量添加到當前的執行環境。

if (true) {

var color = "bule";

}

console.log(color);

function buildUrl() {

var qs = "?debug=true";

with (location) {

var url = href + qs;

}

return url;

}

console.log(buildUrl());

//作用域鏈

var color = "blue";

function changeColor() {

var anotherColor = "red";

function swapColors() {

var tempColor = anotherColor;//創建一個變量；

anotherColor = color;//可以訪問 anotherColor

color = tempColor;//可以訪問color

//可以訪問其他兩個環境是因為是它的父執行環境

}

swapColors();

}

changeColor();

var color = "blue";

function changeColor() {

if (color === "blue") {

color = "red";

return color;

}else {

color = "blue";

return color;

}

console.log(changeColor())

var a = /come on/g;

b = typeof a;

console.log(b);

var one = "one";//刪不了！聲明的全局不發刪！

two = "two";

this.thr = "thr";

delete two;

delete thr;

delete one;

console.log(one);

var o = "object";

function test(o) {

var i = 0;

if (typeof o == "object") {

var j = 0;

for (var k = 0; l < 10; k++) {

console.log(k);

}

console.log(k)

}

console.log(j);

}

console.log(test(o))

var scope = "global scope";

function checkscope() {

var scope = "local scope";

function nested() {

var scope = "nested scope";

return scope;

}

return scope;

}

console.log(checkscope());

var scope = "global";

function checkscope() {

var scope = "local"

return scope;

}

console.log(checkscope());

for (i = 0,j = 10; i < 10; i++, j--){

console.log(i * j);

}

for (i in 0){

console.log(i)

}

var n = 123456.789

a = n.toPrecision(1);

var b = new Date();

a = typeof(b + 1)

a = typeof(b - 1)

a = typeof(b / 1)

a = typeof(b % 1)

a = typeof(b * 1)

a = (b == b.toString())

a = typeof(b > (b-1))

console.log(a)

a = Object(3);

a = 10 + ""

a = + "2312"// Number(a)

a = typeof (a)

var b = 17

a = "0" + b.toString(8);

console.log(a)

//比較2個單獨的數組或對象是否相等

function rui(a,b) {

if (a.length != b.length) return false;

for (var i = 0; i < a.length; i++){

if (a[i] !== b[i]) return false;

}

return true;

}

var a = {x:1};

a.x = 2;

a.y = 3;

console.log(a.value)

//字符串無法更改的..你所更改的其實是創建的一個新的。

var s = "hello";

b = s.toUpperCase();

console.log(s)

console.log(b)

var text = "testing: 1, 2, 3";

var pattern = /\d+/g

a = pattern.test(text)

a = text.search(pattern);

a = text.match(pattern)

a = text.replace(pattern, "#")

a = text.split(/\D+/)

console.log(a)

var a = "\b"

a = "\o"

a = "\t"

a = "\n"

a = "\v"

a = "\f"

a = "\r"

a = "\'"

console.log(a)

var a =

"easdasd\

asdasd\

asdasd"

document.write(a)

console.log(a)

var a = new Date(2011, 0, 1);

a = new Date(2017, 5, 16, 15, 55,30);

b = new Date();

a = b.getFullYear();

a = b.getMonth();

a = b.getDate()

a = b.getTime()

a = b.getDay()

a = b.getHours()

a = b.getUTCHours()

console.log(a)

function rui() {

a = arguments[0] + arguments[1];

return a;

alert(a);//不會執行..

}

console.log(rui('haha' , "xixi"));

//switch 語句

var a = 50;

switch(a) {

case (a = 20):

alert("yes.U Can.");

break;

case ("a = 40 or 50"):

alert("yes.U Can.");

break;

default:

alert("yes.U Can3.");

}

//可以字符串、變量、表達式——case的值

switch("hello world"){

case "hello" + " world":

alert("what?");

break;

case "goodBye":

alert("U Can.");

break;

default:

alert("Yes..U Can..");

}

if (i == 25) {

alert("aaha");

}else if (i == 30) {

alert("asd");

}else if (i == 35){

alert("sad");

}else{

alert("fuck")

}

var i = 5;

switch(i) {

case 25:

alert("what?");

break;

case 30:

alert("aha");

break;

case 35:

alert("asdasd>");

break;

default:

alert("fuck you")

}

var a = 0;

for (var i = 1;i < 10; i++) {

if (i % 5 == 0){

break;

}

a++;

}

console.log(a);

var b = 0;

for (var i = 1;i < 10; i++) {

if (i % 5 == 0) {

continue;

}

b++;

}

console.log(b);

var a = 10

for (var i = 0; i < 10; i++){

}

alert(i);

//全等/不全等

var a = (NaN === NaN)

a = null == undefined

console.log(a);

//減法

var a = 10 - 5;

a = NaN - 5;

a = 10 - NaN;

a = Infinity - Infinity;

a = -Infinity - -Infinity;

a = Infinity - -Infinity;

a = -Infinity - Infinity;

a = +0 - +0;

a = -0 - +0;

console.log(a);

var a = 1 + 2;

a = NaN + 1

a = +0 + -0;

b = 5;

c = 10

a = "I Can.." + b + c

a = "I can.." + (b + c);

console.log(a)

//求模

var a = 26 % 5;

a = Infinity % 5

a = 123 % 0

a = Infinity % Infinity;

a = 100 % Infinity

a = 0 % 100

a = true % 6

console.log(a);

var a = 0/0

a = 21021/0

a = Infinity / 2101201201

console.log(a);

//邏輯非~

var a = (!Object);

a = (!"");

a = (!"asda");

a = (!0);

a = (!"25csaz-=");

a = !null;

a = !false;

a = !undefined;

//邏輯與

var q = false;

a = (q && w);

console.log(a);

var myObject = a`Object || bObject;//本章經常使用此種模式-程序的賦值語句

var b = -2;

b.toString(2);

a = b << 5;

console.log(a);

c = a >> 5;

console.log(c);

d = a >>> 5;

console.log(d);

var a = 25 & 6;//與

console.log(a);

a = 25 | 6;//或

console.log(a);

a = 25 ^ 3;//異或

console.log(a);

var a = 25;

b = ~a;//按位非操作符

console.log(a);

console.log(b);//操作數的負值 - 1；

a = -18;

console.log(a.toString(2));

var a = "01";

b = +a;

a = "1.1";

b = +a;

a = "z";

b = +a;

a = false;

b = +a;

a = 1.1;

b = +a;

a = {

valueOf: function() {

return -1;

}

b = +a;

console.log(b);

// 會自動轉換

var a = "12312";

++a;

a = "asdb";

++a;

a = false;

++a;

a = true;

++a;

a = "0.212";

++a;

a = "0.12";

--a;

a = new Object();

++a;

console.log(a);

var a = new Object();

a.valueOf();

console.log(a);

var a = "This is the letter sigma: \u03a3."

console.log(a);

var a = "123213asdv"//字母將不會錄入(整數)

a = "100.001.123"//只對第一個‘.’有效;

a = "0xA";//16進制始終會被轉換為0；

a = "070";//始終忽略前導的零；（於parseInt 的第二個區別）

a = "abs";//NaN

a = "3.213e10"//e表示法32130000000

console.log(parseFloat(a));

var a = "060";

b = Number(a); //number 是忽略掉前面的0的，除非是 0x

c = parseInt(a,8);

console.log(b);

var a = parseInt("1 2345asdasd");

a = parseInt(".21321");

a = parseInt(" ");

a = parseInt("0xf");

a = parseInt("22.1231312");

a = parseInt("00021231230");

console.log(a);

var a = "abc"

a = "0.5212412"

a = 1.4232

a = true

a = false

a = "0xfa4b"

a = (ha = null)

console.log(Number(a));

var message = 'hello world!'

if (message) {

alert("value is true.")

}

//只有在缺少分號就無法正確解析代碼的時候，JS才會自動填補分號。

var a

console.log(a);

//用Jquery 編寫的 debug 函數~

function debug(msg) {

var log = $("#debuglog");

if (log.length == 0) {

log = $("<div id = 'debuglog'><h1>Debug Log</h1></div>");

log.appendTo(document.body);

}

//在document 中的一個指定的區域輸出調試信息

//如果document 不存在這樣一個區域，則創建一個

function debug(msg) {

//通過查看HTML 元素 id 屬性來查找文檔的調試部分

var log = document.getElementById("debuglog");

//如果這個元素不存在，那麼創建一個

if (!log) {

log = document.createElement("div");//創建一個新的 <div>元素

log.id = "debuglog";//給此元素的 ID 賦值

log.innerHTML = "<h1> Debug Log </h1>";//給此元素初始內容

document.body.appendChild(log);//把這個元素添加到文檔末

}

//將消息包裝在 <pre> 中，並添加到 log 中

var pre = document.createElement("pre");//創建 <pre> 標籤

var text = document.createTextNode(msg);//將msg 包裝在以文本節點中

pre.appendChild(text);//文本添加到 pre

log.appendChild(pre);

}

function hide(e, reflow) {//通過 JavaScript 操縱樣式來隱藏元素 e

if (reflow) {//如果 reflow（第二個參數）是 true

e.style.display = "none";//隱藏這個元素，所占空間消失

}else {

e.style.visibility = "hidden";//將e隱藏，保留其所占空間

}

function highlight(e) {//通過設置 css類來高亮顯示e

//簡單的定義或追加 HTML類屬性

//假設 CSS 樣式表中已有 ‘hilite’類

if (!e.className)e.className = "hilite";

else e.className += "hilite";

}

</script>

Hello

//在document 中的一個指定的區域輸出調試信息

//如果document 不存在這樣一個區域，則創建一個

function debug(msg) {

//通過查看HTML 元素 id 屬性來查找文檔的調試部分

var log = document.getElementById("debuglog");

//如果這個元素不存在，那麼創建一個

if (!log) {

log = document.createElement("div");//創建一個新的 <div>元素

log.id = "debuglog";//給此元素的 ID 賦值

log.innerHTML = "<h1> Debug Log </h1>";//給此元素初始內容

document.body.appendChild(log);//把這個元素添加到文檔末

}

//將消息包裝在 <pre> 中，並添加到 log 中

var pre = document.createElement("pre");//創建 <pre> 標籤

var text = document.createTextNode(msg);//將msg 包裝在以文本節點中

pre.appendChild(text);//文本添加到 pre

log.appendChild(pre);

}

function moveon() {

//通過彈出一個對話框來詢問用戶一個問題？

var answer = confirm("Are you ready? ");

//單擊‘確認’按鈕，瀏覽器會加載一個新頁面

if (answer) window.location = "http://luckyman.xyz";

}

//在一分鐘（6W毫秒）後執行定義的這個函數

setTimeout(moveon, 5000);

//定義一個構造函數以初始化一個新的 Point對象

function Point(x, y) {//照慣例，構造函數均以大寫字母開始

this.x = x;//關鍵字 this 指代初始化的實例

this.y = y;//將函數參數存儲為對象的屬性

}

//使用 new 關鍵字和構造函數來創建一個實例

var p = new Point(1, 1);//平面幾何中的點(1,1)

//通過給構造函數的 prototype 對象賦值給 Point 對象定義方法

Point.prototype.r = function() {

return Math.sqrt(

this.x * this.x +//返回 x2 + y2 的平方根

this.y * this.y//this 指代調用這個方法的對象

);

}

//Point的實力對象p （以及所有的Point 實例對象）繼承了方法 r()

console.log(p.r());

//for 循環的階乘

function factorial2(n){

var i, product = 1;

for (i = 5; i <= n; i++)

product *= i;

return product;

}

console.log(factorial2(10));

//絕對值

function abs(x) {

if (x > 0) {

return x;

}else {

return -x;

}

console.log(abs(-2));

//階乘

function factorial(n) {

var product = 1;

while (n > 1) {

product *= n;

n--;

}

return product;

}

console.log(factorial(10));

var a = [];

a.push(1,2,3);

a.reverse();//反轉

console.log(a);

points.dist = function(){

var p1 = this[0];

var p2 = this[1];

var a = p2.x - p1.x;

var b = p2.y - p1.y;

return Math.sqrt(a * a + b * b);

}

points.dist();

function rui(x) {

return x + 1;

}

function Rui(x) {

return x * x;

}

console.log(Rui(rui(5)));

var x = 2, y = 3, a;

a = (x == y);

a = (x != y);

a = (x < y);

a = (x <= y);

a = (x > y);

a = (x >= y);

a = ("two" == "three");

a = ("two" > "thrr");

a = (false == (x > y));

a = ((x == 2) && (y == 3));

a = ((x > 3) || (y < 3));

a = (!(x == y));

console.log(a);

</script>

javascript

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