2016 Update

Task/Kaprekar-numbers/JavaScript/kaprekar-numbers-1.js

@@ -0,0 +1,12 @@
+function isKaprekar( n, bs ) {
+	if ( n < 1 ) return false
+	if ( n == 1 ) return true
+	bs = bs || 10
+	var s = (n * n).toString(bs)
+	for (var i=1, e=s.length; i<e; i+=1) {
+		var a = parseInt(s.substr(0, i), bs)
+		var b = parseInt(s.substr(i), bs)
+		if (b && a + b == n) return true
+	}
+	return false
+}

Task/Kaprekar-numbers/JavaScript/kaprekar-numbers-2.js

@@ -0,0 +1,11 @@
+function isKaprekar( n, bs ) {
+	if ( n < 1 ) return false
+	if ( n == 1 ) return true
+	bs = bs || 10
+	for (var a=n*n, b=0, s=1; a; s*=bs) {
+		b += a%bs*s
+		a = Math.floor(a/bs)
+		if (b && a + b == n) return true
+	}
+	return false
+}

Task/Kaprekar-numbers/JavaScript/kaprekar-numbers-3.js

@@ -0,0 +1,12 @@
+function kaprekar( s, e, bs, pbs ) {
+	bs = bs || 10; pbs = pbs || 10
+	const toString = n => n.toString(pbs).toUpperCase()
+	document.write('start:',toString(s), ' end:',toString(e), ' base:',bs, ' printBase:',pbs, '<br>' )
+	for (var k=0, n=s; n<=e; n+=1) if (isKaprekar(n, bs)) k+=1, document.write(toString(n), ' ')
+	document.write('<br>found ', k, ' numbers<br><br>')
+}
+
+kaprekar( 1, 99 )
+kaprekar( 1, 255, 16)
+kaprekar( 1, 255, 16, 16)
+kaprekar( 1, 288, 17, 17)