js数组添加有长度但是没有数据

js 有长度但是没有数据，考虑到是可能是异步问题或者深拷贝，但是不知道怎么修改

    let candidates = [2, 3, 6, 7]
    let target = 7
    let path = []
    let sum = 0
    let startindex = 0
    var res = []
    function backTracing(candidates, target, sum, startindex) {
        if (sum > target) {
            return
        }
        if (sum === target) {
            res.push(path)
            console.log(path);
            return res
        }

        for (let i = startindex; i < candidates.length; i++) {
            path.push(candidates[i])
            sum += candidates[i]
            // console.log(sum);
            backTracing(candidates, target, sum, i)
            sum -= candidates[i]
            path.pop()
        }

        return res
    }


    abc = backTracing(candidates, target, sum, startindex)

        console.log(abc);let candidates = [2, 3, 6, 7]
    let target = 7
    let path = []
    let sum = 0
    let startindex = 0
    var res = []
    function backTracing(candidates, target, sum, startindex) {
        if (sum > target) {
            return
        }
        if (sum === target) {
            res.push(path)
            console.log(path);
            return res
        }

        for (let i = startindex; i < candidates.length; i++) {
            path.push(candidates[i])
            sum += candidates[i]
            // console.log(sum);
            backTracing(candidates, target, sum, i)
            sum -= candidates[i]
            path.pop()
        }

        return res
    }


    abc = backTracing(candidates, target, sum, startindex)

        console.log(abc);