JS - Loop over array of object and output the property

Question

How can I loop over this array of objects and output the key of the object

var people = [
  { name: "jon", age: 42 },
  { name: "mary", age: 32 }
]

so the above would return:

// "name" "age", "name" "age"

thanks Satpal. But I see your method actually converts the properties on the object into array items. — swisstony
– swisstony, Commented Aug 24, 2018 at 10:11

user10243107 · Accepted Answer · 2018-08-24 09:56:31Z

1

You can iterate over the array and use the for ... in loop to output the keys.

var people = [
  { name: "jon", age: 42 },
  { name: "mary", age: 32 }
]

people.forEach(function(element) {
  for (let key in element) {
    console.log(key);
  }
});

answered Aug 24, 2018 at 9:56

user10243107

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Comments

Arup Rakshit · Accepted Answer · 2018-08-24 10:03:31Z

1

Use Object.keys() to extract keys from an object.

var people = [
  { name: "jon", age: 42 },
  { name: "mary", age: 32 }
]

console.log(people.map(o => Object.keys(o).join(" ")).join(", "));

Another example to match the exact output:

var people = [{
  name: "jon",
  age: 42
}, {
  name: "mary",
  age: 32
}]

var result = people.map(o => Object.keys(o).map(string => `"${string}"`).join(' ')).join(', ');
console.log(result);

edited Aug 24, 2018 at 10:03

answered Aug 24, 2018 at 9:58

Arup Rakshit

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