CODEWITHSUNDEEP
javascriptdojojavascript-framework
gk1
gk1

Reputation: 149

javascript code explanation

Can someone explain to me what this code does?

dojo[(show ? "remove" : "add") + "Class"](this.listNode, "tweetviewHidden");

Here's the function in which this function value belongs to:

// Provide the class
dojo.provide("tweetview._ViewMixin");
 
// Declare the class
dojo.declare("tweetview._ViewMixin", null, {
    // Returns this pane's list
    getListNode: function() {
        return this.getElements("tweetviewList",this.domNode)[0];
    },
    // Updates the list widget's state
    showListNode: function(show) {
        dojo[(show ? "remove" : "add") + "Class"](this.listNode, "tweetviewHidden");
    },
    // Pushes data into a template - primitive
    substitute: function(template,obj) {
        return template.replace(/\$\{([^\s\:\}]+)(?:\:([^\s\:\}]+))?\}/g, function(match,key){
            return obj[key];
        });
    },
    // Get elements by CSS class name
    getElements: function(cssClass,rootNode) {
        return (rootNode || dojo.body()).getElementsByClassName(cssClass);
    }
});

Source: http://dojotoolkit.org/documentation/tutorials/1.6/mobile/tweetview/starting_tweetview

Upvotes: 1

Views: 574

Answers (4)

Stephen Chung
Stephen Chung

Reputation: 14605

It "toggles" the class via the "show" variable. That is, if "show" is truthy, then the class will be removed from the node, otherwise it will be added to the node.

Consider using the following shortcut:

dojo.toggleClass(this.listNode, "tweetviewHidden", !show);

Upvotes: 0

user216441
user216441

Reputation:

It uses the [] brackets and the ?: ternary operator, to do something like this:

if(show){
    dojo.removeClass(this.listNode, "tweetviewHidden");
}else{
    dojo.addClass(this.listNode, "tweetviewHidden");
}

Upvotes: 1

japrescott
japrescott

Reputation: 5015

quite simple, if show is true, it will call dojo.removeClass(this.listNode, "tweetviewHidden"); and if its false, it will call dojo.addClass(this.listNode, "tweetviewHidden");. Essentially its a toggling function.

the [ ] brackets open up an object to access the value by key. just like var bla={"foo":"bar"}; bla["foo"];. Now, since its dojo, the value is a function, which will be executed

Upvotes: 2

Kerrek SB
Kerrek SB

Reputation: 476970

Slightly more verbosely, the code does something like this:

if (show) { f = dojo["removeClass"]; }
else      { f = dojo["addClass"];    }

f(this.listNode, "tweetviewHidden");

I suppose dojo acts as a container for functions that can be looked up by name via [].

Upvotes: 1

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