Empty Function Parameters

[empiresolutions]

How do i declare a default value in a function? I have a simple function

function color_input(id,token){
 
    if (!empty(token)){
        document.getElementById(id).style.backgroundColor = '#2A2A2A';
        document.getElementById(id).style.color = '#DDC58C';
    }else{
        document.getElementById(id).style.backgroundColor = '';
        document.getElementById(id).style.color = '';
    }
 
}
 

Called in HTML like

<input type="text" id="example_name" onblur="color_input('example_name');">

You will notice that the #2 parameter is missing in the html call. Sometimes i don't have it to send. in PHP i would just set the functions second param like token=''

function color_input(id,token=''){}

How do i set a default param in a JS function?

[gits]

here is a short example:

function foo(param) {
    // when param is missing set a default-value
    if (typeof param == 'undefined') {
        param = 'default_value';
    }
}

kind regards

[Dormilich]

another variation thereof is:

function foo(param) {
    param = param || 'default_value';
}

[acoder]

No, that would be unreliable with any falsy arguments - see http://bytes.com/topic/javascript/an...tion-arguments

[Dormilich]

I've seen this appoach mostly in cases, where you test for an object.

[acoder]

It'll work in those cases, but where the variable evaluates to false, e.g. false, 0, "", it will take the default instead of the actual value passed.

[Dormilich]

that is correct.

(20 chars min)

[empiresolutions]

thanks much for the insight.

This will be adding this to my function.

if (typeof token != 'undefined')