Lodash _.set() Method

What You’ll Learn

By the end of this tutorial, you’ll use _.set() to write values at nested paths without manual object building.

What Is _.set()?

_.set() is Lodash’s nested write helper. You pass an object, a path, and a value; Lodash walks (or creates) the path and assigns the value at the end. It is the write counterpart to _.get() and pairs naturally with _.result() for read/invoke operations.

Use it for user profiles, configuration trees, form state patches, and any time you would otherwise write fragile chains like obj.a = obj.a || {}; obj.a.b = value.

📝 Syntax

The signature is three arguments—object, path, and value:

_.set(object, path, value)

Syntax Rules

• object — the object to modify (mutated in place).
• path — dot string ("profile.name"), array (["profile", "name"]), or bracket form ("users[0].name").
• value — any JavaScript value to assign at the resolved location.
• Return value — the same object reference (for chaining).
• Missing segments — Lodash creates plain objects or array slots as needed.

import set from "lodash/set";

const user = {};

set(user, "profile.name", "John Doe");
set(user, ["profile", "age"], 30);

// user -> { profile: { name: "John Doe", age: 30 } }

Examples Gallery

Practical _.set() patterns with sample output and interactive Try It Yourself labs.

const user = {};

_.set(user, "profile.name", "John Doe");
_.set(user, ["profile", "age"], 30);

console.log(user);
// -> { profile: { name: "John Doe", age: 30 } }

{ profile: { name: "John Doe", age: 30 } }

const user = {
  profile: {
    address: { city: "New York" }
  }
};

_.set(user, "profile.name", "John Doe");

console.log(user);
// -> {
//      profile: {
//        address: { city: "New York" },
//        name: "John Doe"
//      }
//    }

profile.address.city: "New York"
profile.name: "John Doe"

const user = {};

_.set(user, "profile.name.first", "John");
_.set(user, "profile.name.last", "Doe");

console.log(user);
// -> { profile: { name: { first: "John", last: "Doe" } } }

{ profile: { name: { first: "John", last: "Doe" } } }

const data = {};

_.set(data, "users[0].name", "Alice");
_.set(data, "users[1].name", "Bob");

console.log(data);
// -> { users: [{ name: "Alice" }, { name: "Bob" }] }

{ users: [{ name: "Alice" }, { name: "Bob" }] }

const config = {};

_.set(config, "app.theme.primaryColor", "#3366FF");
_.set(config, "app.debug", true);

console.log(config);
// -> { app: { theme: { primaryColor: "#3366FF" }, debug: true } }

{
  app: {
    theme: { primaryColor: "#3366FF" },
    debug: true
  }
}

const original = {};
_.set(original, "user.name", "Alice");
_.set(original, "user.age", 25);

const transformed = {};
_.set(transformed, "profile", _.get(original, "user"));

console.log(transformed);
// -> { profile: { name: "Alice", age: 25 } }

{ profile: { name: "Alice", age: 25 } }

📝 Notes

• _.set() mutates the target object—clone first when immutability matters.
• Missing intermediate keys are created automatically as plain objects (or array slots).
• Setting a path overwrites the previous value at the final key.
• Primitives along the path may be replaced if Lodash needs to continue deeper.
• Use the same path formats as _.get() for consistency.
• For custom intermediate objects (Maps, special merge rules), use _.setWith().

💡 Best Practices