How to Check if a Value Exists in an Object in JavaScript

Because JavaScript is a dynamically typed language, we can't sure of the type of an object.

Without knowing the object's type, it also means we don't know what properties or values it contains.

In this post, we'll learn how to check if a value exists inside an object in JavaScript.

How to check if a value exists in an object in JavaScript

Let's say we have an object like this:

JAVASCRIPT
const object = {
    name: "John",
    age: 30
};

We can check if a value exists in an object by first getting all of the values with Object.values() and then using the includes() method.

JAVASCRIPT
const object = {
    name: "John",
    age: 30
};

if (Object.values(object).includes("John")) {
    console.log("Value exists");
} else {
    console.log("Value does not exist");
}

BASH
Value exists

You can tell it works because if we try using another name, it won't work:

JAVASCRIPT
const object = {
    name: "John",
    age: 30
};

if (Object.values(object).includes("Jane")) {
    console.log("Value exists");
} else {
    console.log("Value does not exist");
}

BASH
Value does not exist

Alternatively, we can just iterate over the keys of an object and use the .some() function to check if the value exists:

JAVASCRIPT
const object = {
    name: "John",
    age: 30
};

if (Object.keys(object).some((key) => object[key] === "John")) {
    console.log("Value exists");
} else {
    console.log("Value does not exist");
}

BASH
Value exists

We can turn this into a reusable function:

JAVASCRIPT
const object = {
    name: "John",
    age: 30
};

const valueExists = (obj, value) => Object.keys(obj).some((key) => obj[key] === value);

if (valueExists(object, "John")) {
    console.log("Value exists");
} else {
    console.log("Value does not exist");
}

BASH
Value exists

Conclusion

In this post, we learned how to check if a value exists in an object in JavaScript.

We can use the Object.values() method to get all of the values in an object and then use the includes() method to check if a value exists, or we can use the Object.keys() method to get all of the keys in an object and then use the some() method to check if a value exists.

Thanks for reading!

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