deindent.js

var splitRE = /\r?\n/g
var emptyRE = /^\s*$/
var needFixRE = /^(\r?\n)*[\t\s]/

module.exports = function deindent( str ) {
	if (!needFixRE.test( str )) {
		return str
	}
	var lines = str.split( splitRE )
	var min = Infinity
	var type,
		cur,
		c
	for (var i = 0; i < lines.length; i++) {
		var line = lines[i]
		if (!emptyRE.test( line )) {
			if (!type) {
				c = line.charAt( 0 )
				if (c === ' ' || c === '\t') {
					type = c
					cur = count( line, type )
					if (cur < min) {
						min = cur
					}
				} else {
					return str
				}
			} else {
				cur = count( line, type )
				if (cur < min) {
					min = cur
				}
			}
		}
	}
	return lines.map( function( line ) {
		return line.slice( min )
	} ).join( '\n' )
}

function count( line, type ) {
	var i = 0
	while (line.charAt( i ) === type) {
		i++
	}
	return i
}