Lodash _.omitBy() Method

What You’ll Learn

By the end of this tutorial, you’ll use _.omitBy() to remove object properties based on dynamic rules—not just fixed key names.

What Is _.omitBy()?

_.omitBy() is Lodash’s predicate-driven omit helper. Instead of listing exact key names like _.omit(), you pass a function. Lodash walks each own enumerable string key on the object; if your predicate returns a truthy value for that property, it is left out of the result.

Reach for _.omitBy() when removal rules depend on values, key naming patterns, or runtime flags—for example stripping every key that starts with password or dropping null fields from a form payload.

📝 Syntax

The signature pairs an object with one predicate function:

_.omitBy(object, predicate)

Syntax Rules

• object — source object to process (not mutated).
• predicate(value, key) — called for each own enumerable string key.
• Truthy return — property is omitted from the result.
• Falsy return — property is copied into the new object.
• Shallow — top-level keys only; nested objects are not traversed.

import omitBy from "lodash/omitBy";

const user = {
  id: 1,
  username: "john_doe",
  email: "john@example.com",
  isAdmin: true
};

const publicUser = omitBy(user, (value, key) => key === "isAdmin");
// -> { id: 1, username: "john_doe", email: "john@example.com" }

Examples Gallery

Real-world _.omitBy() patterns with sample output and interactive Try It Yourself labs.

const user = {
  id: 1,
  username: "john_doe",
  email: "john@example.com",
  isAdmin: true
};

const publicUser = _.omitBy(user, (value, key) => key === "isAdmin");

console.log(publicUser);
// -> { id: 1, username: "john_doe", email: "john@example.com" }

{ id: 1, username: "john_doe", email: "john@example.com" }

const product = {
  id: 1,
  name: "Laptop",
  price: 999,
  isAvailable: true,
  isFeatured: false
};

const catalogItem = _.omitBy(product, (value, key) => key.startsWith("is"));

console.log(catalogItem);
// -> { id: 1, name: "Laptop", price: 999 }

{ id: 1, name: "Laptop", price: 999 }

const edgeCase = {
  a: null,
  b: undefined,
  c: 0,
  d: "",
  e: false
};

const cleaned = _.omitBy(edgeCase, _.isNil);
// -> { c: 0, d: "", e: false }

// ⚠ Avoid value => !value — it also omits 0, "", and false

{ c: 0, d: "", e: false }

app.get("/user/:id", (req, res) => {
  const userData = fetchUserFromDb(req.params.id);

  const safe = _.omitBy(userData, (value, key) =>
    key.startsWith("password") || key.startsWith("internal")
  );

  res.json(safe);
});

// passwordHash, internalNotes removed
{ id: 42, username: "john_doe", email: "john@example.com" }

const formState = {
  title: "My post",
  subtitle: "",
  tags: ["lodash"],
  notes: null,
  published: false
};

const payload = _.omitBy(formState, (value) =>
  value === "" || value === null || value === undefined
);

// -> { title: "My post", tags: ["lodash"], published: false }

{ title: "My post", tags: ["lodash"], published: false }

const stats = { views: 10, likes: 0, shares: 5, drafts: 0 };

const nonZero = _.pickBy(stats, (value) => value > 0);
// -> { views: 10, shares: 5 }

const withoutZeros = _.omitBy(stats, (value) => value === 0);
// -> { views: 10, shares: 5 }

{ views: 10, shares: 5 }

📝 Notes

• Truthy omits—the predicate returning true means exclude that key.
• _.omitBy() is non-mutating and works on top-level keys only.
• value => !value removes 0, false, and ""—often not what you want.
• Prefer _.isNil when you only mean null and undefined.
• Keep predicates fast on large objects; avoid heavy work inside the callback.
• For a fixed key list, _.omit() is simpler and easier to read.

💡 Best Practices