js删除数组指定元素

js的基本课

长度length定义删除尾部

var arr = ['a','b','c'];
arr.length = 2;
console.log(arr[2]); //为 undefined

delete 删除法, 元素占位,长度不变

var arr= ['a','b','c'];
delete arr[0];
console.log(arr); // [undefined,'b','c']

pop()栈 弹出最后一元素并删除之

var arr = ['a','b','c'];
var one = colors.pop();
console.log(one); // "c"
console.log(arr.length); // 2

shift()队列 抽出第一个元素并删除之

var arr = ['a','b','c'];
var one = colors.shift();
console.log(one); // "a"
console.log(arr.length); // 2

foreach查找删除

var arr = ["a", "b", "c"];

arr.forEach(function(item, index, arr) {
    if(item === "a") {
        arr.splice(index, 1);
    }
});

filter过滤删除

var arr = ["a", "b", "c"];
arr = arr.filter(function(item) {
    return item != "a"
});
console.log(arr); // ["b", "c"]

splice之删除

//删除起始下标为1,长度为2的一个值(len设置2) 
var arr2 = ['a','b','c','d'] 
arr2.splice(1,2); 
console.log(arr2); 
//['a','d']

替换

var arr2 = ['a','b','c','d'];
arr2.splice(1,2,'ttt');
console.log(arr2);
//['a','ttt','d'] 替换起始下标为1,长度为2的两个值为‘ttt',len设置的1

插入

var arr = ['a','b','c','d']; 
arr.splice(1,0,'ttt'); 
console.log(arr); 
//['a','ttt','b','c','d'] 表示在下标为1处添加一项'ttt'

点赞

发表评论

电子邮件地址不会被公开。必填项已用 * 标注