1,为数组实现数组去重功能
<script type="text/javascript">
Array.prototype.removeDuplicate = function () {
let newArr = []
for (let index = 0; index < this.length; index++) {
if(newArr.indexOf(this[index]) == -1){
newArr.push(this[index])
}
}
return newArr
}
var newarr = [1,2,1,3,2,1,3].removeDuplicate()
console.log(newarr,'newarr') //[1, 2, 3] 'newarr'
</script> Array.prototype.removeDuplicate = function () {
return Array.from(new Set(this))
}
var newarr = [1,2,1,3,2,1,3].removeDuplicate()
console.log(newarr,'newarr1') //[1, 2, 3] 'newarr1'
2, 求出所有参数中偶数之和，参数个数不定
<script type="text/javascript">
function sumEven(){
console.log(arguments.length,'arguments')
let sum = 0
for (let num = 0; num < arguments.length; num++) {
if(arguments[num] % 2 == 0){
sum += arguments[num]
}
}
console.log(sum,'sum')
return sum
}
sumEven() //0
sumEven(1,2,5) // 2
sumEven(-2,0,3,1,8,2) //8
</script>实现一个自动生成ID的函数，每次调用ID值加1
<script type="text/javascript">
var getId = (function(){
var num = 0
return function conId(){
return num++
}
})()
getId() //0
getId() //1
getId() //2
</script>
