Tag Archives: Class

Day 31, review sprint

For whatever reason, it was decided that instead of doing another Ruby sprint, we will do a review sprint instead. I was totally unprepared for this. Anyway, let’s just face it.

About 7 students were getting ready for the upcoming Quora contest on machine learning. I didn’t participate since I would be out of town on the day of contest. Oh, well…

The master says, get back to work. Yes, master. I finished the regex sprint and implemented a prefix tree. My data structure skills are kind of average and totally needs more attention. I end up pairing with Al on the prefix tree and he is a great pair to work with 🙂

Subclassing in JavaScript


// In JS, method is a free agent, unlike some other languages

var obj ={

  cat: 'mii',

  cow: 'muu'

};

var shout = function(input){

  console.log(this[input]);

};

obj.shout = shout;

obj.shout('cat');

//or we can call the function in the context of 'obj'

shout.call(obj, 'cat');

As Larry said, this seems to be irrelevant to subclassing, but it is indeed very relevant.

var Phone = function(color){
  this.color = color;
};
Phone.prototype.changeColor = function(newColor){
  this.color = newColor;
  console.log("Phone has a new color: ", this.color);
};

nokiaPhone = new Phone('black');
nokiaPhone.changeColor('grey');

//now subclassing
var SmartPhone = function(color, screenSize){
  Phone.call(this,color); // see the similarity?
  this.screenSize = screenSize;
};
SmartPhone.prototype = Object.create(Phone.prototype);
SmartPhone.prototype.constructor = SmartPhone;
SmartPhone.prototype.changeColor = function(newColor){
  Phone.prototype.changeColor(newColor);
  console.log("I, as a smart phone, am proud of my " + this.screenSize +" inch screen");
};

palmPhone = new SmartPhone('white', 4);
palmPhone.changeColor('red');

Larry also mentioned the beauty of bind. I understand the concept but should have used them more frequently in all the jQuery callbacks.

var obj ={
  cat: 'mii',
  cow: 'muu'
};

var shout = function(input){
  console.log(this[input]);
};

shout('cat'); //undefined
shout = shout.bind(obj);
shout('cat'); //now always run in the context of 'obj'

Oh, for our entire class with 20+ people, we have 7 client projects to pick from. Everyone is supposed to submit their top 3 choices and we will know the result tomorrow. Since only 7 people will be picked, I guess I should be thinking hard about my Plan B. I am thinking about doing a Flickr client…

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