将数组中的相同元素组合为数组中的一个字符串的更简洁的方法？

Question

I'm trying to learn how to refactor my code, and I have written the following function block:

joinSame = (arr) =>{
    let simplifiedArr = [];
    for(let i=0; i < arr.length; i++){
        const tempLast = arr.lastIndexOf(arr[i]);
        const element = arr[i].toString()
        if(i === tempLast){
            simplifiedArr.push(element);
        } else {
            const tempMultiplier = tempLast-i+1;
            simplifiedArr.push(element.repeat(tempMultiplier));
            i = tempLast;
        }
    }
    return simplifiedArr;
}

The idea is that if I input a sorted array ( [3,3,3,4,'a','a'] ), I want the output to be an array with similar entities combined into a string ( ['333', '4', 'aa'] ). I tried to use the.map and.forEach array method, but my problem is trying to "hop" the index to go to the next unique element.

Am I overcomplicating things by trying to get it to refactor to a.map or.forEach method, or is my code "good" enough to let it go?

Answer 1

You can make use of reduce and then take Object.values :

 const arr = [3,3,3,4,'a','a']; const result = Object.values(arr.reduce((a,b)=>(a[b]=(a[b] || '')+b,a),{})) console.log(result);