JavaScript基础知识
JavaScript基础知识
1 创建脚本块
2 隐藏脚本代码
3 浏览器不支持的时候显示
4 链接外部脚本文件
5 注释脚本
6 输出到浏览器
7 定义变量
8 字符串相加
9 字符串搜索
10 字符串替换
thisVar.replace(“Monday”,”Friday”);
11 格式化字串
12 创建数组
13 数组排序
14 分割字符串
15 弹出警告信息
16 弹出确认框
17 定义函数
18 调用JS函数
19 在页面加载完成后执行函数
20 条件判断
21 指定次数循环
22 设定将来执行
23 定时执行函数
24 取消定时执行
25 在页面卸载时候执行函数
1<script language=”JavaScript”>
2 JavaScript code goes here
3</script>
<script language=”JavaScript”>2
JavaScript code goes here3
</script> 2 隐藏脚本代码
1<script language=”JavaScript”>
2<!--
3 document.write(“Hello”);
4// -->
5</script>
在不支持JavaScript的浏览器中将不执行相关代码<script language=”JavaScript”>2
<!--3
document.write(“Hello”);4
// -->5
</script> 3 浏览器不支持的时候显示
1<noscript>
2 Hello to the non-JavaScript browser.
3</noscript>
<noscript>2
Hello to the non-JavaScript browser.3
</noscript> 4 链接外部脚本文件
1<script language=”JavaScript” src="/”filename.js"”></script>
<script language=”JavaScript” src="/”filename.js"”></script> 5 注释脚本
1
2// This is a comment
3document.write(“Hello”); // This is a comment
4
/*
5
All of this is a comment
7
*/
2
// This is a comment3
document.write(“Hello”); // This is a comment4
/*
5
All of this is a comment7
*/ 6 输出到浏览器
1document.write(“<strong>Hello</strong>”);
document.write(“<strong>Hello</strong>”);7 定义变量
1var myVariable = “some value”;
var myVariable = “some value”; 8 字符串相加
1var myString = “String1” + “String2”;
var myString = “String1” + “String2”; 9 字符串搜索
1<script language=”JavaScript”>
2<!--
3 var myVariable = “Hello there”;
4 var therePlace = myVariable.search(“there”);
5 document.write(therePlace);
6// -->
7</script>
<script language=”JavaScript”>2
<!--3
var myVariable = “Hello there”;4
var therePlace = myVariable.search(“there”);5
document.write(therePlace);6
// -->7
</script> 10 字符串替换
thisVar.replace(“Monday”,”Friday”); 11 格式化字串
1 <script language=”JavaScript”>
2 <!--
3 var myVariable = “Hello there”;
4 document.write(myVariable.big() + “<br>”);
5 document.write(myVariable.blink() + “<br>”);
6 document.write(myVariable.bold() + “<br>”);
7 document.write(myVariable.fixed() + “<br>”);
8 document.write(myVariable.fontcolor(“red”) + “<br>”);
9 document.write(myVariable.fontsize(“18pt”) + “<br>”);
10 document.write(myVariable.italics() + “<br>”);
11 document.write(myVariable.small() + “<br>”);
12 document.write(myVariable.strike() + “<br>”);
13 document.write(myVariable.sub() + “<br>”);
14 document.write(myVariable.sup() + “<br>”);
15 document.write(myVariable.toLowerCase() + “<br>”);
16 document.write(myVariable.toUpperCase() + “<br>”);
17
18 var firstString = “My String”;
19 var finalString = firstString.bold().toLowerCase().fontcolor(“red”);
20 // -->
21 </script>
<script language=”JavaScript”>2
<!--3
var myVariable = “Hello there”;4
document.write(myVariable.big() + “<br>”);5
document.write(myVariable.blink() + “<br>”);6
document.write(myVariable.bold() + “<br>”);7
document.write(myVariable.fixed() + “<br>”);8
document.write(myVariable.fontcolor(“red”) + “<br>”);9
document.write(myVariable.fontsize(“18pt”) + “<br>”);10
document.write(myVariable.italics() + “<br>”);11
document.write(myVariable.small() + “<br>”);12
document.write(myVariable.strike() + “<br>”);13
document.write(myVariable.sub() + “<br>”);14
document.write(myVariable.sup() + “<br>”);15
document.write(myVariable.toLowerCase() + “<br>”);16
document.write(myVariable.toUpperCase() + “<br>”);17
18
var firstString = “My String”;19
var finalString = firstString.bold().toLowerCase().fontcolor(“red”);20
// -->21
</script> 12 创建数组
1<script language=”JavaScript”>
2<!--
3 var myArray = new Array(5);
4myArray[0] = “First Entry”;
5 myArray[1] = “Second Entry”;
6 myArray[2] = “Third Entry”;
7 myArray[3] = “Fourth Entry”;
8 myArray[4] = “Fifth Entry”;
9 var anotherArray = new Array(“First Entry”,”Second Entry”,”Third Entry”,”Fourth Entry”,”Fifth Entry”);
10// -->
11</script>
<script language=”JavaScript”>2
<!--3
var myArray = new Array(5);4
myArray[0] = “First Entry”;5
myArray[1] = “Second Entry”;6
myArray[2] = “Third Entry”;7
myArray[3] = “Fourth Entry”;8
myArray[4] = “Fifth Entry”;9
var anotherArray = new Array(“First Entry”,”Second Entry”,”Third Entry”,”Fourth Entry”,”Fifth Entry”);10
// -->11
</script> 13 数组排序
1<script language=”JavaScript”>
2<!--
3 var myArray = new Array(5);
4 myArray[0] = “z”;
5 myArray[1] = “c”;
6 myArray[2] = “d”;
7 myArray[3] = “a”;
8 myArray[4] = “q”;
9 document.write(myArray.sort());
10// -->
11</script>
<script language=”JavaScript”>2
<!--3
var myArray = new Array(5);4
myArray[0] = “z”;5
myArray[1] = “c”;6
myArray[2] = “d”;7
myArray[3] = “a”;8
myArray[4] = “q”;9
document.write(myArray.sort());10
// -->11
</script> 14 分割字符串
1<script language=”JavaScript”>
2<!--
3 var myVariable = “a,b,c,d”;
4 var stringArray = myVariable.split(“,”);
5 document.write(stringArray[0]);
6 document.write(stringArray[1]);
7 document.write(stringArray[2]);
8 document.write(stringArray[3]);
9// -->
10</script>
<script language=”JavaScript”>2
<!--3
var myVariable = “a,b,c,d”;4
var stringArray = myVariable.split(“,”);5
document.write(stringArray[0]);6
document.write(stringArray[1]);7
document.write(stringArray[2]);8
document.write(stringArray[3]);9
// -->10
</script> 15 弹出警告信息
1<script language=”JavaScript”>
2<!--
3 window.alert(“Hello”);
4// -->
5</script>
<script language=”JavaScript”>2
<!--3
window.alert(“Hello”);4
// -->5
</script> 16 弹出确认框
1<script language=”JavaScript”>
2<!--
3 var result = window.confirm(“Click OK to continue”);
4// -->
5</script>
<script language=”JavaScript”>2
<!--3
var result = window.confirm(“Click OK to continue”);4
// -->5
</script> 17 定义函数
1<script language=”JavaScript”>
2 <!--
3 function multiple(number1,number2) {
4 var result = number1 * number2;
5 return result;
6 }
7// -->
8</script>
<script language=”JavaScript”>2
<!--3
function multiple(number1,number2) { 
4
var result = number1 * number2;5
return result;6
}7
// -->8
</script> 18 调用JS函数
1<a href=”#” onClick=”functionName()”>Link text</a>
2<a href="/”javascript:functionName"()”>Link text</a>
<a href=”#” onClick=”functionName()”>Link text</a>2
<a href="/”javascript:functionName"()”>Link text</a> 19 在页面加载完成后执行函数
1<body onLoad=”functionName();”>
2 Body of the page
3</body>
<body onLoad=”functionName();”>2
Body of the page3
</body> 20 条件判断
1<script>
2<!--
3 var userChoice = window.confirm(“Choose OK or Cancel”);
4 var result = (userChoice == true) ? “OK” : “Cancel”;
5 document.write(result);
6// -->
7</script>
<script>2
<!--3
var userChoice = window.confirm(“Choose OK or Cancel”);4
var result = (userChoice == true) ? “OK” : “Cancel”;5
document.write(result);6
// -->7
</script>21 指定次数循环
1<script>
2<!--
3 var myArray = new Array(3);
4 myArray[0] = “Item 0”;
5 myArray[1] = “Item 1”;
6 myArray[2] = “Item 2”;
7 for (i = 0; i < myArray.length; i++) {
8 document.write(myArray[i] + “<br>”);
9 }
10// -->
11</script>
12
<script>2
<!--3
var myArray = new Array(3);4
myArray[0] = “Item 0”;5
myArray[1] = “Item 1”;6
myArray[2] = “Item 2”;7
for (i = 0; i < myArray.length; i++) { 8
document.write(myArray[i] + “<br>”);9
}10
// -->11
</script> 12
22 设定将来执行
1<script>
2<!--
3 function hello() {
4 window.alert(“Hello”);
5 }
6 window.setTimeout(“hello()”,5000);
7// -->
8</script>
9
<script>2
<!--3
function hello() { 4
window.alert(“Hello”);5
}6
window.setTimeout(“hello()”,5000);7
// -->8
</script> 9
23 定时执行函数
1<script>
2<!--
3 function hello() {
4 window.alert(“Hello”);
5 window.setTimeout(“hello()”,5000);
6 }
7 window.setTimeout(“hello()”,5000);
8// -->
9</script>
<script>2
<!--3
function hello() { 4
window.alert(“Hello”);5
window.setTimeout(“hello()”,5000);6
}7
window.setTimeout(“hello()”,5000);8
// -->9
</script> 24 取消定时执行
1<script>
2<!--
3 function hello() {
4 window.alert(“Hello”);
5 }
6 var myTimeout = window.setTimeout(“hello()”,5000);
7 window.clearTimeout(myTimeout);
8// -->
9</script>
<script>2
<!--3
function hello() { 4
window.alert(“Hello”);5
}6
var myTimeout = window.setTimeout(“hello()”,5000);7
window.clearTimeout(myTimeout);8
// -->9
</script>25 在页面卸载时候执行函数
1<body onUnload=”functionName();”>
2 Body of the page
3</body>
4
<body onUnload=”functionName();”>2
Body of the page3
</body> 4
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