🎉 now outperforms JSON on size *and* speed!

rewrote stringifier to keep intermediate results in array and replaced join('~') with smart join

performance.html:15 JSON: 200000 parsed in 731ms, 0.003655ms/item
performance.html:23 JSON: 200000 stringified in 448ms, 0.00224ms/item
performance.html:32 v1: 200000 parsed in 1337ms, 0.006685ms/item
performance.html:40 v1: 200000 stringified in 934ms, 0.00467ms/item
performance.html:49 v2: 200000 parsed in 601ms, 0.003005ms/item
performance.html:57 v2: 200000 stringified in 403ms, 0.002015ms/item

lib/jsurl2.js

@@ -89,10 +89,7 @@
 		var out, k, t
 		var c = peek(a)
 		if (!c) {return EOS}
-		if (c === '~') {
-			eatOne(a)
-			out = true
-		} else if (c === '(') {
+		if (c === '(') {
 			eatOne(a)
 			out = {}
 			while (c = peek(a), c && c !== ')') {
@@ -130,6 +127,9 @@
 		} else if (c === '*') {
 			eatOne(a)
 			out = unescape(eat(a))
+		} else if (c === '~') {
+			eatOne(a)
+			out = true
 		} else if (numRE.test(c)) {
 			out = Number(eat(a))
 		} else if (stringRE.test(c)) {
@@ -141,64 +141,82 @@
 	}
 
 	var endTildesRE = /~*$/
-	var TRUEt = TRUE + '~'
-	function encode (v) {
-		var t, a, out, T = typeof v, val
+	function encode (v, out) {
+		var t, a, T = typeof v, val, prefix
 
 		if (T === 'number') {
-			out = isFinite(v) ? v : NULL
+			out.push(isFinite(v) ? v.toString() : NULL)
 		} else if (T === 'boolean') {
-			out = v ? '' : FALSE
+			out.push(v ? '' : FALSE)
 		} else if (T === 'string') {
 			t = escape(v)
 			if (stringRE.test(t)) {
-				out = t
+				out.push(t)
 			} else {
-				out = '*' + t
+				out.push('*' + t)
 			}
 		} else if (T === 'object') {
 			if (!v) {
-				out = NULL
+				out.push(NULL)
 			} else if (v instanceof Date) {
-				out = '_D' + v.toJSON().replace('T00:00:00.000Z', '')
+				out.push('_D' + v.toJSON().replace('T00:00:00.000Z', ''))
 			} else if (Array.isArray(v)) {
-				a = []
+				out.push('!')
 				for (var i = 0; i < v.length; i++) {
 					t = v[i]
 					// Special case: only use full -T~ in arrays
-					a[i] = t === true ? TRUEt : encode(t)
+					if (t === true) {
+						out.push(TRUE)
+					} else {
+						encode(t, out)
+					}
 				}
-
-				out = '!' + a.join('')
+				out.push('')
 			} else {
-				a = []
+				out.push('(')
 				for (var key in v) {
 					if (v.hasOwnProperty(key)) {
 						t = v[key]
 						if (t !== undefined && typeof t !== 'function') {
-							val = encode(t)
-							a.push(escape(key) + '~', val)
+							out.push(escape(key))
+							encode(t, out)
 						}
 					}
 				}
-				t = a.join('').replace(endTildesRE, '')
-
-				return '(' + t + ')'
+				while(out[out.length - 1] === '') {
+					out.pop()
+				}
+				out.push(')')
 			}
 		} else {
 			// function, undefined
-			out = UNDEF
+			out.push(UNDEF)
 		}
-		return out + '~'
 	}
 
-	var allTerminatorsRE = /\)*~*$/
+	const closeObjRE = /\)+$/g
+	const noTilde = {'!': true, '(': true, ')': true}
 	exports.stringify = function (v, options) {
-		var r = encode(v)
-		if (options && options.short) {
-			return r.replace(allTerminatorsRE, '')
+		var out = [], t, str = '', len, sep = false, short = options && options.short
+		encode(v, out)
+		len = out.length - 1
+		// until where we have to stringify
+		while(t = out[len], t === '' || (short && t === ')')) {
+			len--
+		}
+		// extended join('~')
+		for (var i = 0; i <= len; i++) {
+			t = out[i]
+			if (sep && t !== ')') {
+				str += '~'
+			}
+			str += t
+			sep = !(t === '!' || t === '(' || t === ')')
+		}
+		if (!short) {
+			str += '~'
 		}
-		return r.replace(endTildesRE, '~')
+		return str
 	}
 
 	exports.parse = function (s, options) {