Javascript forEach - how to loop an object? [duplicate]

Question

How can I use forEach to loop an object?

For instance:

var dataset = {
    "data" : {
        "particles" : {},
        "no2" : {},
        "timestamp" : {}
    }
};

js:

dataset.data.forEach(function(field, index) {
    console.log(field);
});

error:

Uncaught TypeError: dataset.data.forEach is not a function

Any ideas?

forEach is a method of array, not of object..Use for-in loop of Object.keys(OBJECT).forEach — Rayon
– Rayon, Commented Jun 29, 2016 at 3:57
This has been answered before: stackoverflow.com/questions/14379274/javascript-iterate-object — BhathiyaW
– BhathiyaW, Commented Jun 29, 2016 at 3:59

mwilson · Accepted Answer · 2019-04-12 15:16:50Z

13

You need to use a for loop instead.for of or for in are good candidates .forEach is not going to work here...

const dataset = {
    "data" : {
        "particles" : {},
        "no2" : {},
        "timestamp" : {}
    }
};

// for in
for (const record in dataset.data) {
  if (dataset.data[record]) {
    console.log(record);
  }
}

// for of
for (const record of Object.keys(dataset.data)) {
  if (record) {
    console.log(record);
  }
}

You may have to do some additional work or provide a better explanation on what you're trying to solve if you want something more specific.

edited Apr 12, 2019 at 15:16

answered Jun 29, 2016 at 3:59

mwilson

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