JavaScript中的forEach数组函数

Question

I have a method code like below.

static transformModel(control: AbstractControl,companyId:number):aDTO[]
{
    let finalRequestObj: aDTO[] = new Array();
    let request: aDTO;
    let counter: number = 0;
    let questionArray = [1,2,3,4,5,6,7];

    questionArray.forEach( num =>{
            counter= counter+1;
            request={
                userSeqId:0,//should be updated on server side
                companyId: companyId,
                questionId : counter,
                versionNumber : eueVersion,
                answer  :  findAnswer(counter,control),
                confirmTimeStr : "",
                screen : SCREEN
            };
            if(request.answer) {
                finalRequestObj.push(request);
            }
        }
    )

    return finalRequestObj;
}

In above method how can I not use counter variable and use the questionArray values to assign to questionId inside request object?

Answer 1

The forEach array method has a second parameter that gets passed to it that represents the index of each element:

questionArray.forEach( (num, counter) =>{
            request={
                userSeqId:0,//should be updated on server side
                companyId: companyId,
                questionId : counter,
                versionNumber : eueVersion,
                answer  :  findAnswer(counter,control),
                confirmTimeStr : "",
                screen : SCREEN
            };
            if(request.answer) {
                finalRequestObj.push(request);
            }
        }
    )

Answer 2

If you want to use the values inside the array, just use the value num provided by forEach , like this:

questionArray.forEach( num =>{
        request={
            // ...
            questionId : num,
            // ...
        };
       //...
    }
)

---

On the other hand if you want to use something like an auto-incremental value taking the array as reference, use the value index provided by forEach as second argument, like this:

questionArray.forEach( (num, index) =>{
        request={
            // ...
            questionId : index,
            // ...
        };
       //...
    }
)

Answer 3

I think what you want is index ( foreach ), then so :

questionArray.forEach( (num, index) =>{
   // use index variable
}