Node.js: for each … in not working

pvorb picture pvorb · Aug 25, 2011 · Viewed 239.3k times · Source

I wanted to use for each ... in with Node.js (v0.4.11).

I use it like this:

var conf = {
   index: {
      path: {
         first: "index.html",
         pattern: "index/{num}.html"
      },
      template: "index.tpl",
      limit: 8
   },
   feed: {
      path: "feed.xml",
      template: "atom.tpl",
      limit: 8
   }
}

for each (var index in conf) {
  console.log(index.path);
}

I get the following error:

        for each (var index in conf) {
     ^^^^

node.js:134
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
SyntaxError: Unexpected identifier
    at Module._compile (module.js:397:25)
    at Object..js (module.js:408:10)
    at Module.load (module.js:334:31)
    at Function._load (module.js:293:12)
    at require (module.js:346:19)
    at Object.<anonymous> (/home/paul/dev/indexing/lib/Index.js:3:13)
    at Module._compile (module.js:402:26)
    at Object..js (module.js:408:10)
    at Module.load (module.js:334:31)
    at Function._load (module.js:293:12)

Where is the mistake? for each ... in is supported since Javascript 1.6.

See MDN for information about the usage of for each ... in.

Answer

S M picture S M · Aug 25, 2011

Unfortunately node does not support for each ... in, even though it is specified in JavaScript 1.6. Chrome uses the same JavaScript engine and is reported as having a similar shortcoming.

You'll have to settle for array.forEach(function(item) { /* etc etc */ }).

EDIT: From Google's official V8 website:

V8 implements ECMAScript as specified in ECMA-262.

On the same MDN website where it says that for each ...in is in JavaScript 1.6, it says that it is not in any ECMA version - hence, presumably, its absence from Node.