使用Array.prototype.reduce()做数组去重或者数组出现个数的案例
//例子
const numberArray = [0, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 1, 2, 3, 1, 1, 2, 2, 0, 0, 0];
const stringArray = ['a', 'a', 'b', 'c']
//计数操作
console.log(
numberArray.reduce((obj, arrayItem) => {
if (!obj[arrayItem]) {
obj[arrayItem] = 0
}
obj[arrayItem]++
return obj
}, {})
) //{"0":4,"1":6,"2":9,"3":2}
//去重操作
console.log(
stringArray.reduce((obj, item) => {
if (obj.indexOf(item) === -1) {
obj.push(item)
}
return obj
},[])
)//["a","b","c"]
