Why using "const" construction in JavaScript is a bad practice?

google-style-guide, javascript

Solution

Because it is not standard (yet). It's a JavaScript 1.5 keyword, not ECMAScript. From the MDN documentation:

The current implementation of `const` is a Mozilla-specific extension and is not part of ECMAScript 5. It is supported in Firefox & Chrome (V8) and partially supported in Opera 9+ and Safari. It is not supported in Internet Explorer 6-9, or in the preview of Internet Explorer 10. The `const` keyword currently declares the constant in the function scope (like variables declared with var).

Also if you read the section you linked to carefully, the last sentence is:

As for the `const` keyword, Internet Explorer doesn't parse it, so don't use it.

Problem

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