[removed] use either a variable, or if it's undefined, a default string

Question

I have this code:

var phrase = function (variable, defaultPhrase) {
    if (typeof variable === \"undefined\") {
        return defaultPhrase;
    }
    else         


        

Answer 1

It's a javascript error to reference an undefined variable with no scope in your function call. So, if the variable js_shutdown doesn't exist in scope, then this:

Ext.Msg.show({title: phrase(js_shutdown,'Shutdown'), //...

is an error.

For example, this code causes an error on the line that calls the phrase() function:

var Ext = {};
Ext.Msg = {};
Ext.Msg.show = function() {console.log("success")};

function phrase(variable, defaultPhrase) {
    return(variable || defaultPhrase);
}

Ext.Msg.show({title: phrase(js_shutdown,'Shutdown')});​

because the javascript engine isn't able to find js_shutdown in any scope.

But, this is OK:

var Ext = {};
Ext.Msg = {};
Ext.Msg.show = function() {console.log("success")};

function phrase(variable, defaultPhrase) {
    return(variable || defaultPhrase);
}

Ext.Msg.show({title: phrase(window.js_shutdown,'Shutdown')});​

You can see that this works here: http://jsfiddle.net/jfriend00/JFz6R/

Because you've told the JS engine exactly where to look for js_shutdown and when it isn't there, it just passes undefined to the phrase function (as you want).