Detect version of JavaScript

Question

How can I detect what version of JavaScript the browser supports (if any)? I want to check for ECMAScript 3 versus ECMAScript 5 versus ECMAScript 6.

Note: I want to

Answer 1

Here is a good reference for you: http://www.docsteve.com/DocSteve/Samples/JS/js_version.html

Basically, use the deprecated language attribute of the script tag

<script language="javascript">var js_version="1.0"</script>
<script language="javascript1.1">var js_version="1.1"</script>
<script language="javascript1.2">var js_version="1.2"</script>
<script language="javascript1.3">var js_version="1.3"</script>
<script language="javascript1.4">var js_version="1.4"</script>
<script language="javascript1.5">var js_version="1.5"</script>
<script language="javascript1.6">var js_version="1.6"</script>

Answer 2

The solution proposed to http://www.docsteve.com/DocSteve/Samples/JS/js_version.html as simple JavaScript function (using "createElement" construction):

<script type="text/javascript">
function get_js_version ()
{
    this.jsv = {
            versions: [
                "1.1", "1.2", "1.3", "1.4", "1.5", "1.6", "1.7", "1.8", "1.9", "2.0"
            ],
            version: ""
        };

    var d = document;

    for (i = 0; i < jsv.versions.length; i++) {
        var g = d.createElement('script'),
            s = d.getElementsByTagName('script')[0];

            g.setAttribute("language", "JavaScript" + jsv.versions[i]);
            g.text = "this.jsv.version='" + jsv.versions[i] + "';";
            s.parentNode.insertBefore(g, s);
    }

    return jsv.version;
}

document.write('JavaScript Version: ' + get_js_version());
</script>

Answer 3

This pops out an alert box with the javascript version being used by your browser:

<script type="text/javascript">
  var jsver = 1.0;
</script>
<script language="Javascript1.1">
  jsver = 1.1;
</script>
<script language="Javascript1.2">
  jsver = 1.2;
</script>
<script language="Javascript1.3">
  jsver = 1.3;
</script>
<script language="Javascript1.4">
  jsver = 1.4;
</script>
<script language="Javascript1.5">
  jsver = 1.5;
</script>
<script language="Javascript1.6">
  jsver = 1.6;
</script>
<script language="Javascript1.7">
  jsver = 1.7;
</script>
<script language="Javascript1.8">
  jsver = 1.8;
</script>
<script language="Javascript1.9">
  jsver = 1.9;
</script>


<script type="text/javascript">
  alert(jsver);
</script>

Related jsfiddle.net

Answer 4

I suppose it depends on what you want to do with the information, but many people prefer to do feature detection, instead of figuring out what browser someone is using or what version of JS.

Check out Modernizr, which is a great library that does feature detection for you.