"Uncaught Typeerror: number[i] is Undefined"

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I am creating a calculator and on my console I only get the error:

Uncaught TypeError: number[i] is undefined.

The code returns the expected working, but this error persists.

Follows the code:

let number = document.getElementsByClassName('number')

let calAction = function(){ 
    console.log('work')
}


function getNumberLoad(number){
    for(let i = 0; i <= number.length; i++)
        number[i].addEventListener('click', calAction, false)        
}

document.addEventListener('DOMContentLoaded', getNumberLoad(number), false)
javascript

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  • The number of loops in the for is wrong when using <= you have defined one item more than the limit of found elements, the count is from 0, so the length has to be less and not less-or-equal. Should be for(let i = 0; i < number.length; i++)

1 answer

1


number.length will return the length of the array number. However, since arrays indexes in javascript (and in most programming languages) start with 0 (zero), the last index of the array is equal to its length minus 1. Therefore, the output condition of your for should be i < number.length.

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