util: add sprintf-like format() function

Fixes #1407.

lib/console.js

@@ -20,45 +20,10 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 var writeError = process.binding('stdio').writeError;
-
-// console object
-var formatRegExp = /%[sdj]/g;
-function format(f) {
-  var util = require('util');
-
-  if (typeof f !== 'string') {
-    var objects = [];
-    for (var i = 0; i < arguments.length; i++) {
-      objects.push(util.inspect(arguments[i]));
-    }
-    return objects.join(' ');
-  }
-
-
-  var i = 1;
-  var args = arguments;
-  var str = String(f).replace(formatRegExp, function(x) {
-    switch (x) {
-      case '%s': return String(args[i++]);
-      case '%d': return Number(args[i++]);
-      case '%j': return JSON.stringify(args[i++]);
-      default:
-        return x;
-    }
-  });
-  for (var len = args.length, x = args[i]; i < len; x = args[++i]) {
-    if (x === null || typeof x !== 'object') {
-      str += ' ' + x;
-    } else {
-      str += ' ' + util.inspect(x);
-    }
-  }
-  return str;
-}
-
+var util = require('util');
 
 exports.log = function() {
-  process.stdout.write(format.apply(this, arguments) + '\n');
+  process.stdout.write(util.format.apply(this, arguments) + '\n');
 };
 
 
@@ -66,7 +31,7 @@ exports.info = exports.log;
 
 
 exports.warn = function() {
-  writeError(format.apply(this, arguments) + '\n');
+  writeError(util.format.apply(this, arguments) + '\n');
 };
 
 
@@ -74,7 +39,6 @@ exports.error = exports.warn;
 
 
 exports.dir = function(object) {
-  var util = require('util');
   process.stdout.write(util.inspect(object) + '\n');
 };
 
@@ -105,6 +69,6 @@ exports.trace = function(label) {
 exports.assert = function(expression) {
   if (!expression) {
     var arr = Array.prototype.slice.call(arguments, 1);
-    require('assert').ok(false, format.apply(this, arr));
+    require('assert').ok(false, util.format.apply(this, arr));
   }
 };