JavaScript Excercise

1. What is the difference between the following 2 statements? setTimeout(booyah, 2000);

Solution:- It will call the "booyah" function after 2 seconds. As, we are passing function name only.

setTimeout(booyah(), 2000);

Solution:- It will call the "booyah" function immediately, rather than waiting 2 seconds. As, we are calling the function using '()'.

2. What do the following 2 alerts display (Solutionwer without running the code)? var myfunc = function(a, x) { return a * x; }; var x = myfunc(2, 3); var y = myfunc; alert(x); alert(y(2,3);

Solution:- Both alert functions will display "6". First alert, we are passing the x var refrence and x is calling a function. Second alert, we are calling y var and y is refrence of a function or in other words y is a function.

3. Write functions booyah1 and booyah2 so that in both cases below, an alert box comes up after 2 seconds that says “BOOYAH!” setTimeout(booyah1, 2000); setTimeout(booyah2(), 2000);

Solution:- function booyah1(){ alert("BOOYAH!"); } function booyah2(){ return ()=>alert("BOOYAH!"); }

4. What is "Unobtrusive Javascript"? What is the practical application of Unobtrusive Javascript (and the reasons for using it)?

Solution:-Unobtrusive Javascript is a way to write the javascript code. According to the principles of unobtrusive javascript, JavaScript code should be separate from HTML. Below are the key features behind writing the javascript code in an unobtrusive way: 1. It's separate the code in 3 major categories HTML (UI/Content) , CSS (styling/Presentation) , JavaScript (logic/Behavior). 2. Fast loading, as some of the old browsers don't support JS then at least HTML and CSS will load. 3. Robustness, It's easy to maintain. Multiple developers can update, debug the respective pages separately.