Why Does My JavaScript Function Conflict with a Form Element\'s ID?

JavaScript Function Name Conflicts with Element ID

Problem:
In JavaScript, a function can have the same name as an element ID. However, in some cases, this can lead to errors. Consider the following two code snippets:

// Works as expected
function border(border) { alert(border); }

const select = document.getElementById('border');
select.addEventListener('change', () => border(select.value));

// Fails with "not a function" error
function border(border) { alert(border); }

const form = document.getElementById('border');
form.addEventListener('change', () => border(form.value));

Why does the first snippet work while the second one fails?

Solution:
This issue is caused by a legacy feature introduced in JavaScript versions 1.0 to 1.3. When a form element is part of a form, it inherits the form's properties. One of these properties is the element's name, which can also be used to reference the element.

In the second snippet, the function name "border" conflicts with the form's property of the same name. When the event listener is triggered, JavaScript tries to call the form's "border" property as a function, which fails.

According to the W3C DOM Level 2 HTML Specification, elements can be accessed by their name or ID using the bracket property accessor syntax. However, older browsers extended this feature to form controls, allowing them to be accessed by their name or ID using the dot notation.

Preventing the Conflict:
To avoid this issue, you should ensure that function names do not conflict with element IDs or other JavaScript properties. Additionally, you can use more specific methods, such as document.querySelector(), to locate elements.

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