Avoid Array.prototype.push

Avoid Array.prototype.push. It modifies the array in place, which is asking for trouble. It also returns the array length, not the modified array, which is plain confusing.

Instead, prefer the array spread syntax¹.

const original = ['cat', 'sat']
const modified = [...original, 'mat']

If you need to go old school, there’s Array.prototype.concat.

const original = ['cat', 'sat']
const modified = original.concat(['mat'])