JSFiddle - React, Tailwind, and code Playground

JavaScript

var array = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]];

var target = [9, 10, 11, 12].toString();
for(var i=0; i<array.length; i++) {
   if(target === array[i].toString()) break;
}

if(i >= array.length) {
    console.log("not found");
} else {
    console.log("found at index " + i);
}