Interwave letters

interweave.js

// Given two strings, print all the inter-leavings
// of the Strings in which characters from two strings
// should be in same order as they were in original strings. 
//
// e.g. 
// for "abc", "de", print all of these: 
// adebc, abdec, adbce, deabc, dabce, etc, etc

var s1 = 'abc'
var s2 = 'de'
var output = '';

function interweave(s1, s2, i1, i2, output) {
	if (i1 === s1.length && i2 === s2.length) {
		console.log(output);
	}
	if (i1 < s1.length) {
		interweave(s1, s2, i1+1, i2, output+s1.charAt(i1));
	}
	if (i2 < s2.length) {
		interweave(s1, s2, i1, i2+1, output+s2.charAt(i2));
	}
}

interweave(s1, s2, 0, 0, output)