Error: When using the ajax method, there is an issue with reading the 'forEach' property of an undefined object

Here's the ajax function I'm working with:

<div class="quiz-box"></div>



...

const url = window.location.href

const quizBox = document.getElementById('quiz-box')

let data

$.ajax({
type: 'GET',
url: `${url}data/`,
success: function(response){
// console.log(response)
data = response.data
data.forEach(el => {
for (const [question, answers] of Object.entries(el)){
quizBox.innerHTML = `
<b>${question}</b>
`
}
});
},
error: function(error){
console.log(error)
},
})

This ajax function fetches data from a Django view.

However, running this code results in the following error in the console:

Uncaught TypeError: Cannot read properties of undefined (reading 'forEach') at Object.success at j

at Object.fireWith [as resolveWith]

at x

at XMLHttpRequest.b

What is the cause of this error and how can I fix it?

Answer №1

Utilize the optional chaining (?.) operator to ensure the variable is not null before accessing it.

alter :

data?.forEach(el => {.....

to :

data?.forEach(el => {.....

and be sure to access div correctly by :

altering :

   <div class="quiz-box"></div>

to :

<div id="quiz-box"></div>

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