JSFiddle - React, Tailwind, and code Playground

by Ravindra Athreya

JavaScript

var list = ['csv', 'pdf', 'pdf', 'csv', 'pdf', 'pdf', 'pdf', 'csv'];  

function countInArray(array, extn) {
    var count = 0;
    for (var i = 0; i < array.length; i++) {
        if (array[i] === extn) {
            count++;
        }
    }
    return count;
}

/* alert(countInArray(list, 'csv')); // returns 2 */

var x = ["AccrualRatesTemplate_v1.xlsx", "LicensorRatesTemplate_v1.xlsx", "AccrualRatesTemplate_v2.xlsx",];
var y = [];
for (let i=0; i<x.length; i++) {
	y.push(x[i].substr(0, x[i].lastIndexOf('_')))
}
/* var f = x.substr(0, x.lastIndexOf('_')); */
/* alert(y); */


let hasDup = y.some((val,i)=>{
  return y.indexOf(val)!=i
})

alert(hasDup);