javascript 基础3第13节
<html>
<head>
<title>javascript基础</title>
</head>
<body>
1.流程控制 顺序 选择 循环结构<br/>
<script type="text/javascript">
var score = 50;
/* 多行注释
if ( score > 60 )
{
alert("恭喜，及格了...");
}
*/
// if ... else ... 单行注释
// if ... else if .... else if .... else ...
//switch
// ? :
document.write("成绩是否合格 : " , score > 60 ? '及格':'没通过' ,"<br/>");
// while
// do while
//for( ; ;) break continue 之后的代码不执行
</script>
2.数组<br/>
<script type="text/javascript">
var a = new Array();//创建数组 没有长度 没有类型限制 set list
document.write("a数组的长度 : " , a.length ,"<br/>");
a[0] = 12;
a[1] = 5;
a[10] = 35;
a[2] = '张三';
a[5] = new Date();
document.write("a数组的长度 : " , a.length ,"<br/>");
document.write("a数组的元素 : " , a.toString() ,"<br/>");
var b = new Array(3);
document.write("b数组的长度 : " , b.length ,"<br/>");
b[5] = 100;
document.write("b数组的长度 : " , b.length ,"<br/>");
document.write("b数组的元素 : " , b ,"<br/>");
//a = new Array(5);
a.length = 5;//修改长度
document.write("a数组的元素 : " , a ,"<br/>");
//初始化
var colors = new Array('red','yellow','blue','green','white','black');
colors[6] = "gray";
document.write("colors数组的元素 : " , colors ,"<br/>");
/*
for(var i = 0; i < colors.length; i++ ) {
document.write(i , " : " , colors[i] ,"<br/>");
}
增强的for循环
for(var i in colors) {
document.write( i , " : " , colors[i] , "<br/>"); // i 数组索引
}
*/
var c = [, new Object , , 'a',new Number(80),"yema"];
c[0] = 20;
c[1] = 10;
c[2] = 30;
document.write("c是否是数组 : " , c instanceof Array , "<br/>");
document.write("c数组的元素 : " , c ,"<br/>");
</script>
3.数组的方法<br/>
<script type="text/javascript">
document.write("colors.concat(c) : " , colors.concat(c) ,"<br/>");
document.write("colors.join('->') : " , colors.join('->') ,"<br/>");
document.write("colors.pop() : " , colors.pop() ,"<br/>");
colors.push('abcd');
document.write("colors : " , colors ,"<br/>");
document.write("colors.shift() : " , colors.shift() ,"<br/>");
colors.unshift('oracle');
document.write("colors : " , colors ,"<br/>");
document.write("colors.reverse() : " , colors.reverse() ,"<br/>");
document.write("colors.sort() : " , colors.sort() ,"<br/>");
var d = [11,2,6,34]
document.write("d.sort() : " , d.sort() ,"<br/>");
document.write("colors.slice(2,5) : " , colors.slice(2,5) ,"<br/>");
document.write("======================== <br/>");
//splice
document.write("colors : " , colors ,"<br/>");
colors .splice(1,2);//删除
document.write("colors : " , colors ,"<br/>");
colors.splice(3,0,'java','xml');//添加
document.write("colors : " , colors ,"<br/>");
colors.splice(1,2,'football','swim');//修改
document.write("colors : " , colors ,"<br/>");
</script>
</body>
</html>
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