js 小记

记录一些 巧妙使用数组、字符串方法的方式

1.数组合并

var arr1=[1,2,3];var arr2=[4,5,6];[].push.apply( arr1, arr2 ); //利用apply可以传入数组参数的特点console.log(arr1); //[1,2,3,4,5,6];

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2集合合并

var lis = document.getElementsByTagName("li");var ps = document.getElementsByTagName("p");var arr = [];[].push.apply(arr,lis); //集合不能使用数组的方法，但是集合本身是伪数组，可以遍历，所以可以当做参数传入[].push.apply(arr,ps);

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3.字符串转数组

var arr = 'red,green,blue,yellow'.split(",");console.log(arr); //['red','green','blue','yellow']

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4.计算总和

方法1

var arr = [1,2,3,4,5];var sum = arr.reduce(function (first, second){    return first + second;});console.log(sum); //15

方法2

var arr = [1,2,3,4,5];var sum = eval(arr.join("+"));console.log(sum); //15

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5.二维数组 指定成员 求最大值

var data = [ [ 10, 20 ], [ 15, 13 ], [ 17, 30 ], [ 30, 10 ], [ 20, 15 ] ];var dataMax = Math.max.apply(null, data.map( function ( v ) { return v[ 0 ]}));

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6.插一条正则

1.转换日期

var date = '1991-1-19'.replace( /(\d+)-(\d+)-(\d+)/, '$1年$2月$3日');

2.简单去重

var str = 'aaaabbb....ccdddd....dd...fff...不不不';newStr = str.replace(/\./g, ''); //去除点符号;newStr = str.replace(/(.)\1+/g, '$1');console.log(newStr);