Why does Firefox give a syntax error, class is a reserved identifier?

Question

Opening a file named index.html with the following code on Firefox 43 renders the following error:

    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title></title>
    <script>
    "use strict";
    class RangeIterator {}
    </script>
    </head>
    <body>
    </body>
    </html>

I see the following error in the console:

SyntaxError: class is a reserved identifier

Any idea why I'm getting that error?

Quick tip: Use this table (https://kangax.github.io/compat-table/es6/) to check ES6 features compatibility in browsers, compilers, etc. — Inacio Schweller, Dec 22 '15 at 05:29

Joseph Young · Accepted Answer · 2016-02-21T14:59:24.227

24

Classes aren't supported in Firefox version < 45 according to this

edited Feb 21 '16 at 14:59

answered Dec 22 '15 at 05:23

Joseph Young

2,758
12
23

4

Well that was simple. Thanks. – btelles Dec 22 '15 at 05:26

score 2 · Answer 2 · answered Mar 09 '18 at 12:24

According to Can I Use ES6 classes support form 45 version of Firefox. if 45 version also throws same error like SyntaxError: class is a reserved identifier then its better to convert to ES5.

Babel is a JavaScript compiler. Use it to Transform ES6 to ES5 format BABEL JS (or) ES6Console.

ES2015 classes « Check the below Converted code from ES6 to ES5.

// ES6                              ES5
class Shape {                   "use strict";
  constructor(color) {
    this._color = color;        function _classCallCheck(instance, Constructor) {
                                  if (!(instance instanceof Constructor)) {
                                    throw new TypeError("Cannot call a class as a function");
  }                               }
}                               }
                                var Shape = function Shape(color) {
                                  _classCallCheck(this, Shape);
                                  this._color = color;
                                };

@See

Why does Firefox give a syntax error, class is a reserved identifier?

2 Answers2

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