js常用数组API

数组api

• forEach 遍历数组的所有元素

var arr = ['one','two','three'];
arr.forEach(function(val,index){
    console.log(val) //one,two,three
    console.log(index) //0,1,2
});

• every 用来判断所有的数组元素，都满足一个条件

var resule = arr.every(function(val,index){
    if(index < 1 ){
        return true;
    }
});
console.log(resule) //false

• some 用来判断所有的数组元素，只要有一个满足条件即可

var resule1 = arr.some(function(val,index){
    if(index >= 1){
        return true;
    }
})
console.log(resule1) //true

• sort 数组排序

var arr1 = [1,3,2,10,5];
var resule2 = arr1.sort(function(a,b){
        return a -b //从小到大排序
        // return b -a 从大到小排序
});
console.log(resule2);//[1,2,3,5,10]

• map 将元素重新组装，并返回

var resule3 = arr.map(function(val,index){
    return '<b>'+ val+'</b>'
});
console.log(resule3);//['<b>one</b>','<b>two</b>','<b>three</b>']

• filter 通过某一条件过滤数组

var resule4 = arr.filter(function(val,index){
    if(val === 'two'){
        return true;
    }
});
console.log(resule4); //["two"]