添加push()、unshift()、splice()、concat()

push()方法接收任意數(shù)量的參數(shù)，并將它們添加到數(shù)組末尾，返回?cái)?shù)組的最新長(zhǎng)度

letcolors?=?[];//?創(chuàng)建一個(gè)數(shù)組

letcount?=?colors.push("red","green");//?推入兩項(xiàng)

console.log(count)//?

unshift()在數(shù)組開頭添加任意多個(gè)值，然后返回新的數(shù)組長(zhǎng)度

letcolors?=newArray();//?創(chuàng)建一個(gè)數(shù)組

letcount?=?colors.unshift("red","green");//?從數(shù)組開頭推入兩項(xiàng)

alert(count);//?

splice()傳入三個(gè)參數(shù)，分別是開始位置、0（要?jiǎng)h除的元素?cái)?shù)量）、插入的元素，返回空數(shù)組

letcolors?=?["red","green","blue"];

letremoved?=?colors.splice(1,0,"yellow","orange")

console.log(colors)//?red,yellow,orange,green,blue

console.log(removed)//?[]

concat()首先會(huì)創(chuàng)建一個(gè)當(dāng)前數(shù)組的副本，然后再把它的參數(shù)添加到副本末尾，最后返回這個(gè)新構(gòu)建的數(shù)組，不會(huì)影響原始數(shù)組

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"]

刪除 pop()、shift()、splice()、slice()