How to find the count of images that have same file name?

Question

Can you please help me how to find the no.of images for same file name,

 var images =["Cat.png", "Cock.png","Dog.png","Parrot.png","Penguin.png",
              "Rabbit.png","Parrot.png"];

here I have 7 images in the array... I need count like..

               Cat:1   
               Parrot :2
               Penguin:1 

Please give me the suggestion

Thanks, Rajasekhar

Answer 1

The usual solution is to use an object as a map to make the link between the keys (name of the files) and the count :

var count = {};
for (var i=images.length; i-->0;) {
   var key = images[i].split(".")[0]; // this makes 'Parrot' from 'Parrot.png'
   if (count[key]) count[key]++;
   else count[key] = 1;
}

Then you have, for example count['Parrot'] == 2

Demonstration : http://jsfiddle.net/tS6gY/

If you do console.log(count), you'll see this on the console (Ctrl+Uppercase+i on most browsers) :

EDIT about the i--> as requested in comment :

for (var i=images.length; i-->0;) {

does about the same thing than

for (var i=0; i<images.length; i++) {

but in the other directions and calling only one time the length of the array (thus being very slightly faster, not in a noticeable way in this case).

This constructs is often used when you have a length of iteration that is long to compute and you want to do it only once.

About the meaning of i--, read this.

i-->0 can be read as :

• decrements i
• checks that the value of i before decrement is strictly positive (so i used in the loop is positive or zero)