Function not working if it have parameter

Question

After requesting a json data i run it through function like this

request.onload = function() {
  var mainData = request.response;
  loadNavbar(mainData);
}


function loadNavbar(jsonObj) {
	length = jsonObj.catagories.length;

	for (var i = 0 ; i < length; i++) {
	list = document.createElement("li");
	span = document.createElement("span");

	itemName = mainData.catagories[i].catName;

	span.innerHTML = itemName;

	list.appendChild(span);
	nav.appendChild(list);

	console.log(i)
	}
}

the webpage return error like this:

main.js:21 Uncaught TypeError: Cannot read property 'length' of undefined
    at loadNavbar (main.js:21)
    at XMLHttpRequest.request.onload (main.js:12)

But after i change it to this :

request.onload = function() {
  var mainData = request.response;
  loadNavbar();
}


function loadNavbar() {
	length = mainData.catagories.length;

	for (var i = 0 ; i < length; i++) {
	list = document.createElement("li");
	span = document.createElement("span");

	itemName = mainData.catagories[i].catName;

	span.innerHTML = itemName;

	list.appendChild(span);
	nav.appendChild(list);

	console.log(i)
	}
}

It work accordingly. Can i know what i do wrong in the first snippet?

both code snippet is not working uncaught referenceError:request is not defined — Hitesh Kansagara
– Hitesh Kansagara, Commented Apr 29, 2018 at 9:49
There's no way your second piece of code could work that way. Do you have a gobal variable mainData? — Thomas
– Thomas, Commented Apr 29, 2018 at 10:00
i think you are wrong the first code may work but there is no way to second code to work. — Lia
– Lia, Commented Apr 29, 2018 at 10:03

vvartiainen · Accepted Answer · 2018-04-29 09:46:00Z

1

I'm pretty sure the object you are passing to the function does not contain an array called catagories. I'm suggesting you have a typo there and it is supposed to be called categories instead.

However, more information could be useful. The contents of the mainData object, for example.

answered Apr 29, 2018 at 9:46

vvartiainen

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2 Comments

KX Jaw Over a year ago

this is the mainData

vvartiainen Over a year ago

To me, it looks like you are passing in a JSON array instead of JSON object since the string starts with square bracket [ instead of curly bracket {. Try switching that?

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