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JavaScript Using let with for Loops

Sahan Balasuriya
Sahan Balasuriya
10,115 Points
Posted by Sahan Balasuriya
Sahan Balasuriya
10,115 Points

How does it know which button I clicked?

So I wondering how to the console know which button we clicked. The for loop loops till buttons.length so If I click button how will it know to stop at 5 so that i = 5. I can see the addEventListener but I'm assuming this is only for the alert message.

1 Answer

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

The loop puts a separate listener function on each button, and each function contains the button number inside it. The loop finishes before any buttons can be clicked.

But later, when you click on a button, only the function that was attached to that specific button runs.

Sahan Balasuriya
Sahan Balasuriya
10,115 Points
Sahan Balasuriya
Sahan Balasuriya
10,115 Points

still a it confused, could you show me the listener function

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

The addEventListener takes another function as an argument. This other function is the one that will run when the button is clicked. The important point is that each button has it's own version of this function to run when it is clicked.

Brandon Lopez
Brandon Lopez
2,045 Points
Brandon Lopez
Brandon Lopez
2,045 Points

Steven Parker- So are you saying each button is storing different data? (storing the unique function inside the button) And if so how does the button store data?

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

The addEventListener function stores the function and any variables that are part of the function scope in system memory (not "inside the button"), and associates it with the button. See the documentation page for addEventListener for more details.

Steve Gallant
Steve Gallant
14,943 Points
Steve Gallant
Steve Gallant
14,943 Points

This was so helpful. The video explains what happens but not really why. Thanks!