How to Loop Through Properties of an Object in JavaScript

Easily loop through the properties of an object without including inherited ones with the help of the hasOwnProperty method:

// Loop through object properties without including
// inherited properties

const object = { ... };

for (const key in object) {
    if (object.hasOwnProperty(key)) {
        // work on properties
    }
}

As you can see, for the for statement, the in keyword is used. However, we also have an if statement that checks for hasOwnProperty. This is because the in keyword also includes inherited properties. To filter them out, we need the if statement.

For a simpler solution, you can also use Object.keys with a forEach combined:

Object.keys(object).forEach((key, index) => {
    console.log(`key: ${key}, value: ${object[key]}, index: ${index}`);
});

It has a fairly good global support, also supported in IE down to version 9.

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Resources:

• The in operator in JavaScript
• The hasOwnProperty method in JavaScript
• Documentation of Object.keys
• Support table for Object.keys