添加push()、unshift()、splice()、concat()
push()方法接收任意数量的参数,并将它们添加到数组末尾,返回数组的最新长度
letcolors = [];// 创建一个数组
letcount = colors.push("red","green");// 推入两项
console.log(count)//
unshift()在数组开头添加任意多个值,然后返回新的数组长度
letcolors =newArray();// 创建一个数组
letcount = colors.unshift("red","green");// 从数组开头推入两项
alert(count);//
splice()传入三个参数,分别是开始位置、0(要删除的元素数量)、插入的元素,返回空数组
letcolors = ["red","green","blue"];
letremoved = colors.splice(1,0,"yellow","orange")
console.log(colors)// red,yellow,orange,green,blue
console.log(removed)// []
concat()首先会创建一个当前数组的副本,然后再把它的参数添加到副本末尾,最后返回这个新构建的数组,不会影响原始数组
letcolors = ["red","green","blue"];
letcolors2 = colors.concat("yellow", ["black","brown"]);
console.log(colors);// ["red", "green","blue"]
console.log(colors2);// ["red", "green", "blue", "yellow", "black", "brown"]
删除 pop()、shift()、splice()、slice()