How do I use the same method when chaining over an object?

Question

var string = function (base) { 
  return { 
    add: function (added) {
      return base + added;
  }
 }
}

text = string("robots").add(" are awesome");

console.log(text);

// robots are awesome

text2 = string("robots").add(" are awesome").add(" everytime!");

console.log(text2);

// TypeError: Object robots are awesome has no method 'add'

How do I make this work? What can you do to share the method 'add' across certain objects within the scope of the function?

Answer 1

If you only return string(base + added). It won't work properly. It'll return an Object when you console.log.

var string = function (base) { 
  return { 
    add: function (added) {
      return string(base + added);
  }
 }
}
console.log(string("test ").add("this ").add("thing"));
// outputs [object Object]

Above example fails for what you want. You may try this:

var string = function (base) { 
  return { 
    add: function (added) {
      base += added;
      return string(this.toString());
    },
   toString: function() {
      return base;
    }
 }
}

console.log(string("test ").add("this ").add("thing").toString());
// outputs "test this thing"

This will output correctly.

You also could extend String.prototype and add the add method.