Understanding Javascript Chaining Patterns

Question

I ran this code into the console and tried calling:

obj.foo().bar().coo().moo();

This was my previous code:

    function bar() {
  this.coo = function () {
    this.moo = function () {
      console.log("yay");
    }
  }
}

obj = {
  foo : function () {this.bar = bar}
};      

The error that returned was "TypeError: Cannot read property 'bar' of undefined". Although, when I wrote:

obj.foo();
obj.bar();
obj.coo();
obj.moo();

It worked fine. Why didn't the first call using method chaining not work as if I was separately calling each method.

Answer 1

You don't return anything. You need to add return this at the end of each of your functions in order to have an object to chain.