Prevent converting string containing an E and numbers to number

Question

We have this 'strange' situation where some product codes, for example 11E6, which are stored in data attributes (ex data-prodcode) are getting converted to 11000000, when retrieved inside jquery click function. Something like this:

    <a data-prodcode="11E6">click</a>
    var code = $(this).data('prodcode');
    console.log(code); --> 11000000

Any advice on how to avoid this behavior or what may cause it?

Ludvig

That's because .data attempts to auto-convert values into numbers or Booleans when possible, and the string 11E6 looks like a number in scientific notation to a computer. – Ilyssa

Answer 1

From the documentation :

Every attempt is made to convert the string to a JavaScript value (this includes booleans, numbers, objects, arrays, and null) otherwise it is left as a string. To retrieve the value's attribute as a string without any attempt to convert it, use the attr() method.

You may use attr in order to avoid automatic parsing :

var code = $(this).attr('data-prodcode');

To be more precise : this shouldn't happen. And in fact it doesn't happen in last versions. Here's the code of current's jQuery (the most interesting part is the comment) :

    if ( typeof data === "string" ) {
        try {
            data = data === "true" ? true :
                data === "false" ? false :
                data === "null" ? null :
                // Only convert to a number if it doesn't change the string
                +data + "" === data ? +data :
                rbrace.test( data ) ? jQuery.parseJSON( data ) :
                    data;
        } catch( e ) {}

And it works in jQuery 1.8 and 1.9 : it doesn't convert the string to a number if a back conversion doesn't produce the same string. But it didn't work in jQuery 1.7.

Knotts

Be sure to add a comment in your code explaining why you're doing this, so some well-meaning optimizer doesn't change it back later on. – Ilyssa

In fact, jQuery's data function is very dangerous for strings in my opinion. It really looks like they were trying to be too smart here... – Revolt

Well, this is probably an edge case. Anyone who NEEDS strings in all cases can and should use your solution, which is probably more efficient than .data anyway. – Ilyssa

@Ilyssa I studied jQuery's code. In fact it was a bug, now fixed (or probably fixed, it's not a so simple code...). – Revolt

Not too smart on our side, the not reading the documentation :) Thanks for ultra fast response/help @ dystroy @Ilyssa – Ludvig