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"

• Satpal: people.forEach( x => console.log(Object.keys(x)))
• swisstony: thanks Satpal. But I see your method actually converts the properties on the object into array items.

Answer 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);
 }
});

Answer 2

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);