Once

Create a function that can only be called once, returning the cached result for subsequent invocations.

Code

Boilerplates

const once = (fn) => {
  let called = false, result;
  return (...args) => {
    if (!called) {
      called = true;
      result = fn(...args);
    }
    return result;
  };
};

let count = 0;
const increment = once(() => ++count);
return [increment(), increment(), increment()].join(',');

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More JavaScript Snippets

Debounce

Create a debounced function that delays execution until after a specified wait period has elapsed since the last call.

Memoize

Cache function results to avoid redundant calculations and improve performance for expensive operations.

Parallel with Limit

Run promises in parallel with a concurrency limit to control resource usage and prevent overwhelming external services.

Promise.allSettled

Wait for all promises to settle, whether they resolve or reject.

Promise.any

Return the result of the first promise that resolves successfully.

Retry with Backoff

Retry an async function with exponential backoff to handle transient failures gracefully.