How can I get data from a field name when the name changes dynamically in Javascript?

Question

I have the following code:

            switch (entityType) {
                case "Exam":
                    entityId = formData.examId;
                    idColumn = 'examId';
                    break;
                case "Subject":
                    entityId = formData.subjectId;
                    idColumn = 'subjectId';
                    break;
            }

It's repeated more times than this but I am just showing two case values here. I believe it's possible to get the values for idColumn by getting the lowercase of entityType and adding Id. But is there a way I could extract the value in formData for the field based on entityType without having to manually code this many times.

Answer 1

You can replace the whole with

  idColumn = entityType.toLowerCase()+'Id';
  entityId = formData[idColumn];

I'd suggest you to read MDN's Working with Objects .

Answer 2

你可以得到它：

entityId = formData[entityType.toLowerCase()+'Id'];

Answer 3

Of course there is! You can use an object just like an array:

idColumn = entityType.toLowerCase() + "Id";
entityId = formData[idColumn];

Answer 4

You can prepare a map and then access the fields directly.

Example:

var map = {
    'Exam': 'examId',
    'Subject': 'subjectId'
}

if (map[entityType]) {
    entityId = formData[map[entityType]];
    idColumn = map[entityType]; 
}
else {
    // error handling
}