TS1308: 'await' has no effect on the type of this expression

What’s happening?

This error occurs when you use await on a value that is not a Promise.

TypeScript detects that the await keyword has no effect because the value is already synchronous.

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Reproduction

function getName(): string {
  return "Alice";
}

async function greet() {
  const name = await getName();
  // ❌ 'await' has no effect on the type of this expression
  console.log(name);
}

getName() returns a plain string, not a Promise<string>, so await is unnecessary.

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Why does TypeScript complain?

TypeScript analyzes the return type:

• Promise<T> → await is needed ✅
• T (non-Promise) → await has no effect ❌

Using await on non-Promise values suggests a misunderstanding of async code.

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Solutions

Option 1: Remove await (recommended)

async function greet() {
  const name = getName(); // ✅ No await needed
  console.log(name);
}

When to use:

• ✅ The function returns a synchronous value
• ✅ Simplest and clearest solution

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Option 2: Make the function async

async function getName(): Promise<string> {
  return "Alice"; // Automatically wrapped in Promise
}

async function greet() {
  const name = await getName(); // ✅ Now await is needed
  console.log(name);
}

When to use:

• ✅ The function will eventually need to be async (e.g., fetching data)
• ✅ You want a consistent async API

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Option 3: Return a Promise explicitly

function getName(): Promise<string> {
  return Promise.resolve("Alice");
}

async function greet() {
  const name = await getName(); // ✅
  console.log(name);
}

When to use:

• ✅ Wrapping synchronous code to match an async interface

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Common scenarios

Awaiting synchronous array methods

const users = ["Alice", "Bob"];
const first = await users[0];
// ❌ 'await' has no effect

// ✅ Fix: Remove await
const first = users[0];

Awaiting a value instead of a Promise-returning function

const result = await fetchData;
// ❌ If fetchData is a Promise, not a function

// ✅ Fix: Call the function
const result = await fetchData();

Mixed sync/async code

async function processData(data: string) {
  const parsed = await JSON.parse(data);
  // ❌ JSON.parse is synchronous

  // ✅ Fix:
  const parsed = JSON.parse(data);
  const validated = await validateData(parsed); // This actually needs await
}

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Key takeaways

• Only use await with Promises
• TypeScript’s error helps you avoid unnecessary await
• If you need async behavior, make the function return a Promise
• Remove await from synchronous operations

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Additional resources

• Async Functions
• Promise