数组扁平化

数组扁平化

//1
const flat1 = (arr)=>{
    return arr.reduce((pre,cur)=>{
        return pre.concat(Array.isArray(cur)?flat1(cur):cur)
    },[])
}
//2 toSting/split
const flat2 = (arr)=>{
    return arr.toString().split(',').map(value=>Number(value))
}
//3 join/split
const flat3 = (arr)=>{
    return arr.join().split(',').map(value=>Number(value))
}
//4 
const flat4 = (arr)=>{
    while(arr.some(value=>Array.isArray(value))){
        arr = [].concat(...arr)
    }
    return arr
}
//5 
const flat5 = (arr) =>{
    while(arr.some(value=>Array.isArray(value))){
        arr.flat()
    }
    return arr
}