【JavaScript笔记】JavaScript基础_数组(8)
这里整理了数组的适用方法。
<!DOCType html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
console.log("--------------------数组Array--------------------");
//数组的创建
var arr = new Array();
console.log(typeof arr); //object
arr[0] = 0;
arr[1] = 1;
arr[2] = 2;
console.log(arr); //(3) [0, 1, 2]
console.log(arr[2]); //2
console.log(arr[3]); //undefined
//[]创建数组
var arr1 = [1, 2, 3, 4, 5];
console.log(typeof arr1); //object
console.log(arr1); //(5) [1, 2, 3, 4, 5]
console.log(arr1.length); //5
//指定索引赋值后的数组长度
arr1[10] = 10;
console.log(arr1.length); //11
console.log(arr1); //(11) [1, 2, 3, 4, 5, , , , , , 10]
//可以修改数组长度
arr1.length = 10
console.log(arr1.length); //10
console.log(arr1); //(10) [1, 2, 3, 4, 5, , , , , ,]
arr1.length = 2
console.log(arr1); //(2) [1, 2]
//给数组的后一个索引赋值
arr[arr.length] = 3;
arr[arr.length] = 4;
console.log(arr.length); //5
console.log(arr); //(5) [0, 1, 2, 3, 4]
//数组可以加属性
var arr2 = new Array();
arr2[0] = 1;
arr2.name = "张三";
console.log(arr2); //(1) [1] {name: '张三'}
//new Array 和 [] 区别
arr = new Array(10, 20, 30, 40, 50);
console.log(arr); //(5) [10, 20, 30, 40, 50]
//new
arr = new Array(10);
console.log(arr); //(10) [undefined, undefined, undefined, undefined, undefined, undefined, undefined, undefined, undefined]
console.log(arr.length); //10
//[]
arr = [10];
console.log(arr); //(1) [10]
console.log(arr.length); //1
//数组可以付不同类型的值，包括对象和数组
arr = [1, "阿", true, null, undefined, { name: "张三" }, [1, 2, 3]];
console.log(arr); //(7) [1, '阿', true, null, undefined, {…}, [1, 2, 3]]
arr = [{ name: "张三" }, function () { console.log("我是函数") }];
console.log(arr); //(2) [{…}, function () {…}]
console.log(arr[0].name); //张三
console.log(arr[1]()); //我是函数
//push: 给数组的后面添加元素
var arr3 = ["张一", "张二", "张三"];
var arr4 = ["李四", "王五", "赵六"];
arr3.push(arr4, "张七");
console.log(arr3); //(7) ["张一", "张二", "张三", ["李四", "王五", "赵六"], "张七"]
arr3 = ["张一", "张二", "张三"];
var result = arr3.push("李四", "王五", "赵六");
console.log(arr3); //(6) ["张一", "张二", "张三", "李四", "王五", "赵六"]
console.log(result); //6 返回长度
//pop: 删除最后一个元素，并返回该元素
var arr4 = ["张一", "张二", "张三", "李四", "王五", "赵六"];
var result = arr4.pop();
console.log(arr4); //(5) ["张一", "张二", "张三", "李四", "王五"]
console.log(result); //赵六
//unshift: 给数组的前面添加元素,并返回数组长度
var arr5 = ["张一", "张二", "张三", "李四", "王五", "赵六"];
result = arr5.unshift("阿", "阿阿");
console.log(arr5); //(8) ["阿", "阿阿", "张一", "张二", "张三", "李四", "王五", "赵六"]
console.log(result); //8
//shift: 删除数组的第一个元素，并返回该元素
var arr6 = ["张一", "张二", "张三", "李四", "王五", "赵六"];
result = arr6.shift();
console.log(arr6); //(5) ["张二", "张三", "李四", "王五", "赵六"]
console.log(result); //"张一"
//array 的遍历
for (let i = 0; i < arr6.length; i++) {
console.log(arr6[i]);
}
//forEach IE8以上才能支持
arr6.forEach(function (value, index, array) {
console.log(value);
console.log(index);
console.log(array);
})
//slice(start, end) 获取选定元素
var arr7 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
result = arr7.slice(1, 4);
console.log(result); //(3) [2, 3, 4]
result = arr7.slice(2);
console.log(result); //(8) [3, 4, 5, 6, 7, 8, 9, 10]
result = arr7.slice(2, -2); //从2开始倒数第2个为止
console.log(result); //(6) [3, 4, 5, 6, 7, 8]
//splice(start, count)
var arr8 = [1, 2, 3, 4, 5, 6, 7];
result = arr8.splice(2, 3);
console.log(result); //(3) [3, 4, 5]
console.log(arr8); //(4) [1, 2, 6, 7]
result = arr8.splice(0, 3);
console.log(result); //(3) [1, 2, 6]
var arr9 = [1, 2, 3, 4, 5, 6, 7];
result = arr9.splice(0, 3, "哈哈", "嘿嘿");
console.log(result); //(3) [1, 2, 3]
console.log(arr9); //(6) ['哈哈', '嘿嘿', 4, 5, 6, 7]
arr9.splice(1, 0, "ok")
console.log(arr9); //(7) ['哈哈', 'ok', '嘿嘿', 4, 5, 6, 7]
//concat() 合并两个数组,
var arr11 = ["张一", "张二", "张三"];
var arr12 = ["李四", "王五", "赵六"];
var result = arr11.concat(arr12, "哈哈", "嘿嘿");
console.log(result); //(8) ['张一', '张二', '张三', '李四', '王五', '赵六', '哈哈', '嘿嘿']
//join(分隔符)
var result = arr11.join("|");
console.log(result); //张一|张二|张三
//reverse() 反转数组
var arr13 = ["张一", "张二", "张三", "李四", "王五", "赵六"];
result = arr13.reverse();
console.log(arr13); //(6) ["赵六", "王五", "李四", "张三", "张二", "张一"]
console.log(result); //(6) ["赵六", "王五", "李四", "张三", "张二", "张一"]
//sort()
var arr14 = [5, 3, 7, 1, 9, 2, 4, 6, 8];
arr14.sort();
console.log(arr14); //(9) [1, 2, 3, 4, 5, 6, 7, 8, 9]
var arr15 = [15, 3, 7, 1, 9, 2, 4, 6, 8];
arr15.sort();
console.log(arr15); //(9) [1, 15, 2, 3, 4, 6, 7, 8, 9]
arr15.sort(function(a,b){
return a - b;
});
console.log(arr15); //(9) [1, 2, 3, 4, 6, 7, 8, 9, 15]
//倒叙排序
arr15.reverse();
console.log(arr15); //(9) [15, 9, 8, 7, 6, 5, 4, 3, 2]
</script>
</head>
<body>
</body>
</html>
欢迎大家的意见和交流
email: li_mingxie@163.com