JavaScript function with 'undefined' parameter [duplicate]
-
09-10-2019 - |
Question
This question already has an answer here:
Going around Modernizr source code I have found strange thing:
window.Modernizr = (function(window,document,undefined) {
After that this function will be called with two arguments (this, this.document
).
Why undefined
is used here? Is it meaningful or it's just strange code-style?
Solution
Creates a local undefined
in case someone redefines undefined
somewhere in the scope chain.
Also provides a faster lookup since undefined
is a global property, so the scope chain traversal is reduced.
Licensed under: CC-BY-SA with attribution
Not affiliated with StackOverflow