Count occurances in string from keyword array in javascript

Question

I have an array:

var locations = ['Afghanistan','Albania','Algeria','New York'];

and a string:

var string = 'I love Afghanistan New York Afghanistan Andorra Andorra Algeria New York';

I want to count the number of times each keyword in the array appears in the string but can't figure out the best way to do that.

Answer 1

Here is my version:

function countItems(a, s) {
    var x, i, output = {};
    for (x = 0; x < a.length; x++) {
        i = 0;
        output[a[x]] = 0;
        while ((i = s.indexOf(a[x], i)) > -1) {
            output[a[x]]++;
            i++
        }
    }
    return output;
}

var result = countItems(locations, string);
// result['Albania'] === 0

Try it out here.