JS: Array.prototype.unshift

xArray.unshift(new1, new2, etc)

• Adds items to the beginning of array xArray.
• Return the new length.

// example of unshift
const xx = [3];
const yy = xx.unshift(7, [8]);
console.log(yy === 3);
console.log(JSON.stringify(xx) === "[7,[8],3]");