Function Names Are Verbs

Function names are verbs

A function does something. Its name must say what it does. Start every function name with a verb.

• validate_payment — not payment_validation.
• buildInvoice — not invoiceBuilder.
• fetchUser — not userData.
• retryUpload — not uploadRetry.

A noun names a thing. Classes, variables, types, modules and files are things. Functions are not.

Not optional

This rule is required. It is not a style preference.

No hook enforces it, so nothing will stop you from skipping it. That makes it easier to drop under time pressure, not less binding.

The test

Read the name aloud with a subject in front of it: "it ____". If the sentence works, the name is a verb.

• "it validates payment" — good.
• "it payment validation" — not a function name.

Booleans are still verbs

is, has, can, should and needs are verbs. Use them.

• isEligibleForRefund, hasActiveSubscription, canDeleteOrder.
• Not eligibility, not activeSubscription, not deletable.

Pick the verb that is true

The verb carries the contract. A wrong verb is worse than a noun.

• get returns something cheap and already present.
• fetch or load crosses a network or a disk.
• build, create, make return a new value.
• update, set, apply change state.
• ensure makes a condition true and is safe to call twice.

handle, process and manage are weak. They fit anything, so they stay true however much the function grows. Prefer the specific verb when one exists: chargeOrder over processOrder. When you keep the weak verb, check the length — see the oversized-function skill.

The exceptions

• Components. A React, Vue or Svelte component is a function, but it names a thing on screen. UserCard, CheckoutForm. Keep the noun.
• Python @property. A property is read like an attribute. total_price, not get_total_price.
• Constructors and factories that carry a type name. Money.of, User.from_row.

Nothing else. A callback is a function: onSubmit is a field, but the function behind it is submitOrder, never submitHandler.

Applying this

• The verb comes first. Then the object it acts on.
• One verb per name. Two verbs means two functions.
• Keep the name inside ten words — see the self-documenting-names skill.