when to use ( ) vs = in javascript?

The simple answer is, they do different things, that why we use them for different reasons. The equals sign is an assignment operator and we use it when we want to assign a value to something. The parantheses are used to call (execute/invoke) a function so we use it when we want to call a function.

Read below for a more detailed response

This is because the = is an assignment operator it's job is to inform that the left side of the argument is equal to whatever is on the right side. So when you are saying var Name = 'Bob'. What you are saying is, take this variable with the name Name and assign it the value Bob.

On the other hand the () indicates that we are calling a function. Basically when we do, console.log('Hi'). We are actually accessing the console object and then retrieving the log property on it, which is actually a function. In order to invoke the function we use the () and add any parameters to it.