between.js

// between.js v1.1.1
function between(number, a, b, orEqual = false) {
	const min = Math.min(a, b),
		max = Math.max(a, b)
	if (orEqual == true) {
		return number >= min && number <= max
	}
	return number > min && number < max
}

Number.prototype.between = function(a, b, orEqual = false) {
	return between(this, a, b, orEqual)
}

String.prototype.between = function(a, b, orEqual = false) {
	return between(this, a, b, orEqual)
}

between.min.js

// between.min.js v1.1.1
function between(c,d,e,f=!1){let g=Math.min.apply(Math,[d,e]),h=Math.max.apply(Math,[d,e]);if(!0==f)return c>=g&&c<=h;return c>g&&c<h}Number.prototype.between=function(c,d,e=!1){return between(this,c,d,e)},String.prototype.between=function(c,d,e=!1){return between(this,c,d,e)};

between(1,0,2) // true
1 its between 0 and 2