Strangest things i found in JavaScript

1. [] + []; // ""
2. {} + {}; // NaN
3. [] + {}; // "[object Object]"
4. {} + []; // 0
5. [] == []; // false
6. [] < []; // false
7. [] > []; // false
8. [] <= []; // true
9. [] >= []; //true
10. Math.min() < Math.max(); // false
11. foo = [0];
12. !foo; // false
13. foo == foo; // true
14. foo == !foo; // true
15. [['0']] == false; // true
16. [['0']] == true; // false
17. typeof NaN; // "number"
18. NaN == true; // false
19. NaN == false; // false
20. NaN != true; // true
21. NaN != false; // true
22. NaN == NaN; // false
23. NaN == !NaN; // false
24. !NaN; // true
25. NaN != NaN; // true
26. 'x' == true; // true
27. 'x' == false; // false
28. '0' == true; // false
29. '0' == false; // true

Couple of interview questions

Write a function that takes an integer (i) and prints out the first 'i' rows of Pascal's Triangle (eg. i =5).

            line = 5;
            var pascalDepth = parseInt(line, 10); //The input integer is provided on a single line as a text value, so this handles it.
            var testTriangle = pascalTriangle(pascalDepth);
            var output = [];
            maxlength = testTriangle.length;
            var html = "<table>"
            for(var i = 0; i < maxlength; i++){
                html += "<tr>";
                html += "<td>";
                html += testTriangle[i];
                html += "</td>";
                html += "</tr>";
            }
            html+= "</table>";

            document.write(html);

            function pascalTriangle(totalLines, triangle) {
                if (typeof triangle === 'undefined') {
                    triangle = [];
                }

                if (triangle.length === totalLines) {
                    return triangle;
                }

                if (triangle.length > 0) {
                    var triangleLine = [];
                    for (var i = 0; i < triangle.length; i++) {
                        if (typeof triangle[triangle.length - 1][i - 1] === 'undefined') {
                            triangleLine.push(1);
                        } else {
                            triangleLine.push((triangle[triangle.length - 1][i - 1] + triangle[triangle.length - 1][i]));
                        }
                    }
                    triangleLine.push(1);
                    triangle.push(triangleLine);
                } else {
                    triangle.push([1]);
                }
                return pascalTriangle(totalLines, triangle);
            }
-----------------------------------------------------------------------------------------

Write a function that prints out a breakdown of an integer into a sum of numbers that have just one non-zero digit.  

eg., given 43018 it should print 40000 + 3000 + 10 + 8.

            var arr = [];
            var i =1;               
            var a = 40118;
            var input = 40118;
            while(a > 0)
            {
            if(a%(Math.pow(10,i)) > 0)
              arr.push(a%(Math.pow(10,i)));       
             
              a = a-a%(Math.pow(10,i++));
            }
            arr.sort(function(a,b){ return b-a;});
            document.write(input +" = " +arr.join(" + "));

Swap 2 numbers without using third variable

This is a very very very simple question generally asked as first level of logical questions

Swap 2 numbers without using third variable


function fnSwap(a,b){
   console.log("Initial value of a: "+ a);
   console.log("Initial value of b: "+ b);

   // swaping the values of a and b
    b = a+b
    a = b-a
    b = b-a
    console.log("Swaped value of a: "+ a);
   console.log("Swaped value of b: "+ b);
}

Input:

fnSwap(10,20);


output:

Initial value of a: 10

Initial value of b: 20

Swaped value of a: 20

Swaped value of b: 10

Note:
It works with console if you are working with firefox install firebug to see output in console
if you install chrome/IE you can use f12 for console

Closing the PopUp and redirecting Parent Window

I have tried for few hours to solve this problem Here is the simple example which helps you to solve the Problem

Problem:
 Create a PopUp window on submission of a value in PopUp the PopUp Closes and the Parent Windows redirects to Some other Page 

Solution:
Here is the simple way to solve it

Create 2 php pages

1. popup.php
Copy this Code

<html>
    <head>    
    </head>
    <body>
        <a href="#" onclick="window.open('popupcode.php','Login','height=500,width=420,scrollbars=yes');return false;">PopUp</a>
    </body>
    </html>