JavaScript – Iterate through Key-Value pairs of Map

To loop/iterate through key-value pairs of a Map in JavaScript, call entries() method on this map which returns an iterator for the key-value pairs in the Map, and use For-of Loop to iterate over the items.

Refer JavaScript For-of Loop.

Syntax

The syntax to use entries() method on a Map map1 to iterate over the key-value pairs using for-of loop is

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for (const x of map1.entries()) {
    //x[0] is the key
    //x[1] is the value
}

Examples

In the following example, we take a Map with keys 'a', 'b', and 'c'. We shall iterate through these key-value pairs using entries() method and for-of loop.

index.html

<!DOCTYPE html>
<html lang="en">
<body>
    <pre id="output"></pre>
    <script>
        var map1 = new Map([
            ['a', 10],
            ['b', 20],
            ['c', 30]
        ]);
        
        var displayOutput = '';
        for (x of map1.entries()) {
            displayOutput += x[0] + ' - ' + x[1] + '\n';
        }
        document.getElementById('output').innerHTML += displayOutput;
    </script>
</body>
</html>

Conclusion

In this JavaScript Tutorial, we learned how to loop through key-value pairs of a Map in JavaScript using entries() method, with examples.