JSFiddle - React, Tailwind, and code Playground

by Gereltod Gotsbayar

JavaScript

var items = [[1,2], [1,4], [2,3], [5,1], [3, 4]];
var counter = [0, 0, 0, 0, 0];
var currentPosition, currentItem;

for (i = 0; i < 5; i++) {
    
    for (j = 0; j < 2; j++) {
        
        currentItem = items[i][j];
        
        if (counter.indexOf(currentItem)) {
            
            
            currentPosition = counter.indexOf(currentItem);
            counter[currentPosition] = counter[currentPosition] + 1;
        } else {
            
            counter.push(currentItem);
        }
    }
}

for (i = 0; i < counter.length; i++) {
    
    alert(counter[i]);
}