JSFiddle - React, Tailwind, and code Playground

by David Thomas

JavaScript

var contains = function(needle, haystack){
    if ([].every){
        return needle.every(function(a){
            return haystack.indexOf(a) > -1;
        });
    }
    else {
        var result = true;
        for (var i = 0, len = needle.length; i < len; i++){
            if (haystack.indexOf(needle[i]) === -1) {
                return false;
            }
        }
        return result;
    }
}
var a1 = [1,2,3],
    a2 = [1,2,3,4];
console.log(contains(a1, a2));