nodejs : TypeError: Object #<Object> has no method 'map'

Question

I'm trying to iterate a json object with nodejs and it's turning out to be a real challenge.

> var fs = require('fs');
> var meta = JSON.parse(fs.readFileSync('path_to_file'));
> typeof meta
'object'
> for ( k in meta)  console.log(k);
key1
key2
> meta.map(function(v,k) { console.log(k +'=' + v); })
TypeError: Object #<Object> has no method 'map'
    at repl:1:7
    at REPLServer.self.eval (repl.js:110:21)
    at Interface.<anonymous> (repl.js:239:12)
    at Interface.EventEmitter.emit (events.js:95:17)
    at Interface._onLine (readline.js:202:10)
    at Interface._line (readline.js:531:8)
    at Interface._ttyWrite (readline.js:760:14)
    at ReadStream.onkeypress (readline.js:99:10)
    at ReadStream.EventEmitter.emit (events.js:98:17)
    at emitKey (readline.js:1095:12)
>

I'm new to node, is this normal ?

user1902830 · Accepted Answer · 2014-06-23 15:15:04Z

1

map is for arrays, you are applying it to an object.

You can try _.map of underscore.js

var _ = require('underscore');
_.map({one: 1, two: 2, three: 3}, function(num, key){ return num * 3; });
=> [3, 6, 9]

answered Jun 23, 2014 at 15:15

user1902830

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2 Comments

haki Over a year ago

Thanks, that's stupid of me. I've tried lodash var _ = require('lodash'); _.map(meta, function(k,v) ... ) and got TypeError: Cannot call method 'map' of undefined... whats the problem man ?

user1902830 Over a year ago

To require a npm module, you have to install it first. Run the command npm install lodash --save in your working directory.

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