jQuery.each is generating a bug with a string parameter

[brabia]

jQuery version

3.1.1

Description

Uncaught TypeError: Cannot use 'in' operator to search for 'length' in this is a string
jQuery.each is generating a bug with a string parameter http://prntscr.com/ib9ngg

How to reproduce it

var jEach = function(a){
	jQuery.each(a, function(){
		console.log(this);
	});
};

jEach(null);
jEach([1,2]);
jEach('[1,2]');
jEach('this is a string');

[mgol]

Strings are not supported parameters to jQuery.each, only objects or arrays. You may only pass parameters documented on https://api.jquery.com, e.g. here https://api.jquery.com/jQuery.each/.

[brabia]

Thanks for your quick response

I know that jQuery.each is supporting an array or an array of objects but by accident instead of using the proper parameter which should be an array in this case, I used a string, so I guess jQuery.each should do nothing here instead of firing an error message.

Thanks again.

[mgol]

jQuery in general doesn't validate its inputs, it just relies on them being correct. Adding consistent validation would increase the library size a lot.

If you want such validation, consider using TypeScript which contains jQuery type definitions in the @types/jquery package.