ES6 展开运算符 三个点实际功能

1.数组中使用
let defaultColors = [‘red‘, ‘greed‘]
let favoriteColors = [‘orange‘, ‘yellow‘]
let fallColors = [‘pink‘, ‘blue‘]

ES5
defaultColors.concat(favoriteColors)

ES6
[...defaultColors , ...favoriteColors ]


ES5
defaultColors.concat(favoriteColors)
defaultColors.concat(fallColors)

ES6
[...defaultColors , ...favoriteColors, ...fallColors  ]

[‘purple‘, ...defaultColors , ...favoriteColors, ...fallColors, ‘black‘ ]        //可在数组中直接放入，还可新增其他字符串

ES5
function addNumber(a, b, c, d, e){
 let numbers = [a, b, c, d, e]
 retrun numbers.reduce((sum, number) => {
   retrun sum + number  
 },0)
}
console.log(addNumber(1,2,3,4,5))

ES6
function addNumber(...numbers){
 retrun numbers.reduce((sum, number) => {
   retrun sum + number  
 },0)
}
console.log(addNumber(1,2,3,4,5))