Need Help with creating dynamic object in react

Need Help with creating dynamic object in react



I am working on one of my side projects , a simple expense tracker with an option of a calendar control and two buttons for adding income and expense. I am using React

for this. Working Code Pen here:

I thought of state structure to be something like this:

   2017:{11:{income:12000,expense:3000},10:{income:5000, expense:200}}

records =>followed by year=>months=actual data
I am calling addIncome and addExpense methods to add the expense and income and they are working fine for me. As both of the methods work in a similar way so I created a function updateState to update the respective state for expense or income.

I need help in line no 115 :

if (key == "expense")
       updatedRecordsForSelectedYear = {
         [selectedMonth]: { expense: parseInt(amount, 10) }
       updatedRecordsForSelectedYear = {
         [selectedMonth]: { income: parseInt(amount, 10) }
Here I have to write if-else block just to create the object expense and income, I want to skip this check, I want to supply direct key here. How can I achieve that? If I pass key , the state is updated with string key and not the actual expense or income.

I have tried following code:
  1. updatedRecordsForSelectedYear = {
    [selectedMonth]: { ${key}: parseInt(amount, 10) }
  2. updatedRecordsForSelectedYear = {
    [selectedMonth]: { key: parseInt(amount, 10) }

None of them works for me. I would be highly obliged if someone helps. Thanks.


To use variables in an objects wrap it inside squares, (like you already did for selectedMonth for example.

So this should be fine (assuming key is a variable you are passing to the method):

updatedRecordsForSelectedYear = {
[selectedMonth]: { [key]: parseInt(amount, 10) }

Have you tried this?


thanks @Marmiz!! This solves it . Thanks so much… I missed that…


Sometimes we get so distracted in the bigger pictures that we loose focus on the small details.

Glad I could have been of help, and happy coding :slight_smile:


Yup, exactly as you said :slight_smile: