Cannot include the = sign outside the bracket

Whenever I click on the = sign it gets included inside the bracket. If you can’t understand, then see below:
Instead of

obj[letter]=i

it is always taking

obj[letter=i]

Here’s a screenshot:

👹👺🧙🏻🫐🍖⛆

Wait is :japanese_ogre::japanese_goblin::mage:t2: