JS: Array.prototype.unshift

xArray.unshift(new1, new2, etc)

• Add 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]");

// example of unshift
const xx = [3, 4];
const yy = xx.unshift(7, [8]);

console.log(yy);
// 4

console.log(xx);
// [ 7, [ 8 ], 3, 4 ]