Why Does My `animate` Function Work in IE But Not Chrome: A JavaScript Shadowing Issue?

JS Function 'Animate' Fails in Chrome But Succeeds in IE: Resolving the Shadowing Issue

Problem Description

An onClick event with an inline function named 'animate' designed to alter the style of an element fails in Chrome but functions as intended in IE. The code invoked within the 'animate' function aims to modify the element's position and color using JavaScript.

function animate() {
  var div = document.getElementById('demo');
  div.style.left = "200px";
  div.style.color = "red";
}

#demo {
  position: absolute;
}

<p></p>

Solution and Explanation

The problem lies in JavaScript's scope chain and shadowing mechanism. When the inline event handler attribute (e.g., onclick) is utilized, the global function 'animate' becomes obscured by the recently introduced 'Element.prototype.animate' method, which stems from the Web Animations API.

window.animate // global function

Element.prototype.animate // element's own method

According to the DOM specifications, the global event handler environment shadows the element's scope during event handling. Thus, the 'animate' method of the element takes precedence over the global 'animate' function.

10. Let the current event handler value be the result of the following steps:
    ...
    4. Let the target environment be the lexical environment scope.
    ...
    6. If the element is non-null, then
        a. Let the target environment be the result of NewObjectEnvironment(the element, the target environment).

To rectify this, one can employ several approaches:

1. Rename the global function:

function animate__() {
  var div = document.getElementById('demo');
  div.style.left = "200px";
  div.style.color = "red";
}

2. Bind the global function to the target element:

document.getElementById('demo').addEventListener('click', animate.bind(document.getElementById('demo')));

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