1.一维数组
设置数组求和
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var weight=[1.3,2.3,3,4,5,3.21321];
var sum=0;
//数组的遍历
for(var i=0;i<weight.length;i++){
sum+=weight[i];
document.write(weight[i]+" ");
}
document.writeln("总体重是"+sum+" "+"平均体重"+(sum/weight.length)+"<br/>");
document.write("体重保留为"+(sum/weight.length).toFixed(3));
</script>
</head>
<body>
</body>
</html>
数组的元素可以为任意元素，元素的值可以为任意的类型，
数组在内存中存在形式，数组为引用类型，
2.数组细节
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var weight = [1,2,3,4,5,6];
var sum = 0;
function abc(arr){
weight[0]=9999;
}
//数组的遍历
abc(weight);
for(var i = 0; i < weight.length; i++) {
document.write(weight[i] + " ");
}
</script>
</head>
<body>
</body>
</html>
js中的数组为引用传递
3.数组的引用基本用法
越界的话会输出undefined
不能访问没定义的元素
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var weight = [1, "hello", 2.5];
window.alert(weight[16]);
</script>
</head>
<body>
</body>
</html>
4.js的数组可以动态的增长
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var weight = [1, "hello", 2.5];
window.alert(weight.length);
weight[3] = 12;
window.alert(weight.length);
</script>
</head>
<body>
</body>
</html>
5.split函数的用法
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var word = "hello world,大家好";
var str = word.split(",");
for(var i = 0; i < str.length; i++) {
document.write(str[i] + "<br/>");
}
</script>
</head>
<body>
</body>
</html>
对字符串进行分割
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var word = "hello world,大家好";
var str = word.split(",");
for(var i = 0; i < str.length; i++) {
document.write(str[i] + "<br/>");
}
var str1=word.split("");
document.write("一个一个的分组"+"<br/>");
for(var i = 0; i < str1.length; i++) {
document.write(str1[i] + " ");
}
str1=word.split(",",3);
document.write(str[0]);
document.write(str1.length);
</script>
</head>
<body>
</body>
</html>
6.遍历数组的方式：var key in arr
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="JavaScript" type="text/jscript">
var word = "hello world,大家好";
var str = word.split(",");
for(var i = 0; i < str.length; i++) {
document.write(str[i] + "<br/>");
}
var str1=word.split("");
document.write("一个一个的分组"+"<br/>");
for(var i = 0; i < str1.length; i++) {
document.write(str1[i] + " ");
}
str1=word.split(",",3);
document.write(str[0]);
document.write(str1.length);
</script>
</head>
<body>
</body>
</html>
原文：https://www.cnblogs.com/helloworld2019/p/10920625.html