JavaScript的数组详解
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创建数组
1.通过new Array()进行创建
var arr1=new Array();
2.通过中括号进行创建
var arr2=[];
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计算数组的长度
var arr3=['1','2','3']; console.log(arr3.length)
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数组的下标
//从0开始,从左到右 var arr4 = ["a","b","c","d"]; console.log(arr4[1])
注意:下标为-1表示没有这个元素,而不是倒数第一个!
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获取成员在数组中的下标 indexOf
var arr=["a","b","c"]; console.log(arr.indexOf("b")) console.log(arr.indexOf("1")) 输出: 1 -1 //当成员不在数组中,则返回-1
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数组的拼接 join
var arr5=["a","b","c"]; console.log(arr5.join("-")) 输出: a-b-c
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数组的反转排列
var arr5=["a","b","c"]; console.log(arr5.reverse()) 输出: ["c", "b", "a"]
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数组的删除元素
splice(删除开始的下标,删除的成员个数)
返回值就是被删除的元素组成的数组
var arr5=["a","b","c","d"]; console.log(arr5.splice(1,2)) console.log(arr5) 输出: ["b","c"] ["a","d"]
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在数组的任意位置添加元素
splice(要插入的下标位置,0,[插入的元素])
var arr5=["a","b","c","d"]; console.log(arr5.splice(1,0,"x","y","z")) //0表示不删除元素!1表示插入的位置! console.log(arr5)
输出:
[] //表示没有删除的元素
["a", "x", "y", "z", "b", "c", "d"] //在下标为1的地方插入"x","y","z
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在数组的末尾添加元素
push 表示给数组新增成员,返回结果是新的成员的数量!
var arr5=["a","b","c",]; var ret=arr5.push("d"); console.log(arr5) console.log(ret) 输出: ["a", "b", "c", "d"] 4
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移除数组的最后一个成员
pop,返回值是被移除的元素!
var arr5=["a","b","c"]; var ret=arr5.pop(); console.log(ret) console.log(arr5) 输出: c ["a", "b"]
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多维数组
多维数组就是数组的嵌套。二维数组就是嵌套两层,三维数组就是嵌套三层。
var arr5=[ ["a","b","c"], ["1","2","3"], ["x","y","z"] ]
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多维数组成员的获取
var arr5=[ ["a","b","c"], ["1","2","3"], ["x","y","z"] ] console.log(arr5[1][2]) 输出: 3
代码成就万世基积沙镇海,梦想永在凌云意意气风发。