How to implement chained method calls like jQuery?

Question

So I am (still) completely in love with the almighty jQuery, and I have my own growing library of utilities that I want to codify in a java-script object. And I would like to keep syntax similar to that of jquery for the sake of simplicity for my other front end devs. So I want something like this:

 foo(argument).method(argument);

I have been trying something like this:

var foo = function(str){
    this.str = str;
}

foo.prototype = {
    alertTest  :  function(additional){
         alert(this.str + ' ' + additional);
    }
}

So that foo('hello').alertTest('world); with alert 'hello world'

I know this is possible, but I am not an OO guy and need help getting this simple thing right. Please help. I also intend on having many foo().bar(); type functions, like foo().somethingelse(); and foo().anotherthing(); . I have made several attempts, but am struggling hard here. Also there must be an awesome tight way of doing it.

Thanks folks!

Answer 1

You are almost there:

new foo('hello').alertTest('world');

or if you don't like the new:

var bar = function bar(str) {
    this.str = str;    
};

bar.prototype = {
    alertTest :  function(additional){
        alert(this.str + ' ' + additional);
        return this;
    }
};

function foo(str) {
    return new bar(str);
}

foo('hello').alertTest('world');

Live Demo.

Answer 2

I did something like this a while ago and it was a ton of fun to create!

If i remember correctly, To be able to use dot-operators, I had to return the object as part of the original function call. This way I could chain lots of stuff together like $(id).value('asdf').color('#ff0000')

function $(id){
    this.e = document.getelementbyid(id)
    me = this
    this.val = function (newval) {
        this.e.value = newval;
        return me;  // <- Important
    };
    return this;  //  <- Important
}

$("textbox1").val("New Value")    // changes textbox1's value to "New Value"

If it helps for reference: http://www.mikedoesweb.com/vis/

Answer 3

Something I did really quick but you can relate to the essence of what we are trying to achieve here -

function ChainingObj() {
  if (!(this instanceof ChainingObj)) {
    return new ChainingObj();
  }
}

ChainingObj.prototype.first = function() {
  console.log("foo");
  return this; //important to return this.
}


ChainingObj.prototype.second = function() {
  console.log("bar");
  return this;
}

var a = ChainingObj().first().second();