经常用到,记一笔
1、object
var jone={
name:'Jone',
age:"18",
sex:"male",
weight:'70kg'
};
var skills=['vue','react','angular','jquery','bootstrap'];
delete jone.sex;
//输出
//var jone={
//name:'Jone',
//age:"18",
//weight:'70kg'
//};
delete skills[1];
//输出skills=['vue',empty,'angular','jquery','bootstrap'];
//其中empty的判断可以理解为undefined。
2、array
//删除首位
var skills=['vue','react','angular','jquery','bootstrap'];
skills.shift();//返回 "vue"
//打印skills,skills.length
//输出["react", "angular", "jquery", "bootstrap"],length=4;
skills.pop();//返回 "bootstrap"
//打印skills,skills.length
//输出["react", "angular", "jquery"],length=3;
//删除任意项
数组.splice(起始下标(必填),要删除的元素个数(必填,0则不删),"要从起始下标开始添加的元素(选填,可以同时加多个)")
//返回你选中要删除的数组元素,以数组格式返回;
//执行后数组直接更新
skills=['vue','react','angular','jquery','bootstrap'];
skills.splice(1,1)//返回["react"]
//打印skills,skills.length
//输出 ["vue", "angular", "jquery", "bootstrap"],length=4;
skills.splice(1,2,'1','2','3')//返回["angular", "jquery"]
//打印skills,skills.length
["vue", "1", "2", "3", "bootstrap"],length=5;