Chrome doesn't declare my JavaScript function

Question

There's problem when I test my code on Google Chrome and I don't have any problem when test it on Firefox. I've a function and I call it in onblur event. It's working fine on Firefox but Google Chrome gave me this error on the console

Uncaught ReferenceError: fill is not defined

HTML code:

<input type="text" name="title" id="title" placeholder="mytitle" onblur='fill(this);'>

JavaScript code:

function fill(element,value = false){
    if(element.value == ""){
        $("#"+element.id).css('border-color','red');
    }else{
        $("#"+element.id).css('border-color','#56de56');
    }
    if(value == true){
        if(element.value > 75 || element.value < 5)
            $("#"+element.id).css('border-color','red');
    }
}

and I declared fill function before that line and after that line so I'm facing the same problem.

Fabrício Matté · Accepted Answer · 2013-08-16 19:02:37Z

3

EcmaScript, the standard JS is based on as of version 5.1 does not support optional parameters.

function fill(element,value = false){

Does not do what you expect it to. Instead, you have to do this manually:

function fill(element,value){
     if(typeof value === 'undefined') {
          value = false;
     }

Or in a shorter notion if you're only expecting boolean values

function fill(element,value){
    value = value || false;

Note - These both have cases they miss - as Fabrício Matté suggested in the comments you can also check arguments.length if you want to differenciate not getting an argument passed, and getting undefined explicitly although that's rarely the case.

^{although optional parameters are in the EcmaScript 6 proposal}

(Firefox however, does independently support them even today)

edited Aug 16, 2013 at 19:02

Fabrício Matté

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answered Aug 16, 2013 at 18:51

Benjamin Gruenbaum

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6 Comments

Fabrício Matté Over a year ago

You meant the ECMAScript 5.1 spec I believe.

Benjamin Gruenbaum Over a year ago

@FabrícioMatté right you are, mixed up what I thought about and what I wrote - started writing "You can't do optional parameters in JavaScript yet" and changed my mind. Thanks for the catch!

Yahia Over a year ago

@BenjaminGruenbaum really !! .. ok i will test it without optional parameter

Benjamin Gruenbaum Over a year ago

@YahiaSweid-BillGates It's one of those cases where Firefox developers at mozilla eagerly implemented a language feature that made it through to the ECMAScript 6 draft :)

Fabrício Matté Over a year ago

You can also use if (arguments.length < 2), in the rare case when passing undefined as the value argument must be treated differently from omitting the argument.

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