JavaScript基础知识-优快云博客

本文详细介绍JavaScript的基础语法，包括脚本创建、隐藏与显示控制、变量定义、字符串操作、数组使用及排序、弹窗与确认框展示、函数定义与调用等核心功能。

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1 创建脚本块

JavaScript code goes here
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</script>

2 隐藏脚本代码

<!--
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document.write(“Hello”);
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// -->
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</script>

在不支持JavaScript的浏览器中将不执行相关代码

3 浏览器不支持的时候显示

<noscript>
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Hello to the non-JavaScript browser.
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</noscript>

4 链接外部脚本文件

5 注释脚本

// This is a comment
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document.write(“Hello”); // This is a comment
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/**//*
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All of this is a comment
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6 输出到浏览器

document.write(“<strong>Hello</strong>”);

7 定义变量

var myVariable = “some value”;

8 字符串相加

var myString = “String1” + “String2”;

9 字符串搜索

<!--
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var myVariable = “Hello there”;
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var therePlace = myVariable.search(“there”);
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document.write(therePlace);
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// -->
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</script>

10 字符串替换

thisVar.replace(“Monday”,”Friday”);

11 格式化字串

<!--
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var myVariable = “Hello there”;
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document.write(myVariable.big() + “<br>”);
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document.write(myVariable.blink() + “<br>”);
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document.write(myVariable.bold() + “<br>”);
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document.write(myVariable.fixed() + “<br>”);
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document.write(myVariable.fontcolor(“red”) + “<br>”);
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document.write(myVariable.fontsize(“18pt”) + “<br>”);
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document.write(myVariable.italics() + “<br>”);
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document.write(myVariable.small() + “<br>”);
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document.write(myVariable.strike() + “<br>”);
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document.write(myVariable.sub() + “<br>”);
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document.write(myVariable.sup() + “<br>”);
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document.write(myVariable.toLowerCase() + “<br>”);
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document.write(myVariable.toUpperCase() + “<br>”);
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var firstString = “My String”;
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var finalString = firstString.bold().toLowerCase().fontcolor(“red”);
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// -->
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</script>

12 创建数组

<!--
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var myArray = new Array(5);
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myArray[0] = “First Entry”;
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myArray[1] = “Second Entry”;
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myArray[2] = “Third Entry”;
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myArray[3] = “Fourth Entry”;
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myArray[4] = “Fifth Entry”;
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var anotherArray = new Array(“First Entry”,”Second Entry”,”Third Entry”,”Fourth Entry”,”Fifth Entry”);
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// -->
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</script>

13 数组排序

<!--
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var myArray = new Array(5);
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myArray[0] = “z”;
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myArray[1] = “c”;
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myArray[2] = “d”;
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myArray[3] = “a”;
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myArray[4] = “q”;
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document.write(myArray.sort());
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// -->
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</script>

14 分割字符串

<!--
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var myVariable = “a,b,c,d”;
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var stringArray = myVariable.split(“,”);
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document.write(stringArray[0]);
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document.write(stringArray[1]);
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document.write(stringArray[2]);
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document.write(stringArray[3]);
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// -->
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</script>

15 弹出警告信息

<!--
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window.alert(“Hello”);
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// -->
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</script>

16 弹出确认框

<!--
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var result = window.confirm(“Click OK to continue”);
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// -->
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</script>

17 定义函数

<!--
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function multiple(number1,number2)

{
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var result = number1 * number2;
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return result;
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}
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// -->
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</script>

18 调用JS函数

<a href=”#” onClick=”functionName()”>Link text</a>
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19 在页面加载完成后执行函数

<body onLoad=”functionName();”>
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Body of the page
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</body>

20 条件判断

<script>
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<!--
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var userChoice = window.confirm(“Choose OK or Cancel”);
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var result = (userChoice == true) ? “OK” : “Cancel”;
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document.write(result);
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// -->
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</script>

21 指定次数循环

<script>
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<!--
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var myArray = new Array(3);
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myArray[0] = “Item 0”;
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myArray[1] = “Item 1”;
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myArray[2] = “Item 2”;
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for (i = 0; i < myArray.length; i++)

{
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document.write(myArray[i] + “<br>”);
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}
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// -->
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</script>
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22 设定将来执行

<script>
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<!--
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function hello()

{
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window.alert(“Hello”);
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}
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window.setTimeout(“hello()”,5000);
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// -->
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</script>
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23 定时执行函数

<script>
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<!--
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function hello()

{
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window.alert(“Hello”);
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window.setTimeout(“hello()”,5000);
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}
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window.setTimeout(“hello()”,5000);
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// -->
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</script>

24 取消定时执行

<script>
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<!--
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function hello()

{
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window.alert(“Hello”);
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}
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var myTimeout = window.setTimeout(“hello()”,5000);
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window.clearTimeout(myTimeout);
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// -->
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</script>

25 在页面卸载时候执行函数

<body onUnload=”functionName();”>
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Body of the page
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</body>
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