Answers for "how to check if 2 values are available in array javascript"

javascript get elements that exist in two arrays

function getArraysIntersection(a1,a2){
    return  a1.filter(function(n) { return a2.indexOf(n) !== -1;});
}
var colors1 = ["red","blue","green"];
var colors2 = ["red","yellow","blue"];
var intersectingColors=getArraysIntersection(colors1, colors2); //["red", "blue"]

js check if all array values are the same

const allEqual = arr => arr.every( v => v === arr[0] )
allEqual( [1,1,1,1] )  // true