Christos Ploutarchou

Here some very common tasks how to iterating over an JavaScript object properties

If you have an object, you can’t just iterate it using map(), forEach() or a for..of loop.

You will get the following errors:

const items = {
  'date': new Date(),
  'number': 2,
  'sampleString': 'test'
}

map() function will give you TypeError: items.map is not a function:

items.map(item => {})

forEach()  function will give you TypeError: items.forEach is not a function:

items.forEach(item => {})

for..of  will give you TypeError: items is not iterable:

for (const item of items) {}

So, what can you do to iterate?

for (const item in items) {
  console.log(item)
}

You can also do ti by call Object.entries() function to generate an array with all its enumerable properties, and loop through that, using any of the above methods:

Object.entries(items).map(item => {
  console.log(item)
})

Object.entries(items).forEach(item => {
  console.log(item)
})

for (const item of Object.entries(items)) {
  console.log(item)
}