Extract list of values from an array of objects to an array based on a key in JavaScript.

There may be a situation where you want to extract the list of values of a specific key from an objects to an array. 



Method 1:

In one way, we can use both for loop and Array.push() method and achieve it. 

For example, we have an Array of objects as below

let studentsObject = [
    {
        "name": "John",
        "age": 26
    },
    {
        "name": "Helen",
        "age": 42
    },
    {
        "name": "Cole",
        "age": 54
    },
    {
        "name": "Noah",
        "age": 38
    }
]

we can extract the values as shown below 

let namesList;
studentsObject.forEach(student => {
    namesList.push(student.name)
});
console.log(namesList);

//Output
['John', 'Helen', 'Cole', 'Noah']

Method 2:

The simple and easy way is using map function as below

let namesList = studentsObject.map(student => student.name);
console.log(namesList);

//Output
['John', 'Helen', 'Cole', 'Noah']

Here we've to assign the map function to a variable. If we don't assign to a variable, then the whole array object will be printed as it is.

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