js问题不会做了 求助

Question

var arr = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];

var sarr = [4,10,18];
想得到5-9  11-17  19-最后
想得到result 数组 
var result = ["fghij","lmnopqr","tuvwxyz"];

sarr可能的值
sarr = [20] 得到21-最后 var result = ["vwxyz"];

sarr = [20,24] 得到21-23 25-最后 var result = ["vwx","z"];

求助js该怎么写

Answer 1

        var arr = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

        var sarr = [4,10,18], result = []


        for(var i = 0, l = sarr.length; i<l ; i++){
            sarr[i+1] = sarr[i+1] ? sarr[i+1] : arr.length
            result[i] = arr.slice(sarr[i]+1,sarr[i+1]).join('')
        }
        console.log(result)

Answer 2

var arr = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];

var sarr = [20] ;

function StrArr(arr, sarr) {
    var rs = []
    for (var i = 0; i < sarr.length; i++) {
        if(i == sarr.length -1)//判断是否为 sarr数组 最后一个
            rs.push(arr.slice(sarr[i]+1).join(''))
        else 
            rs.push(arr.slice(sarr[i]+1,sarr[i+1]).join(''))
    }
    return rs;
}


console.log(StrArr(arr, sarr));