The snippet library.
Small, practical examples. Search by task or narrow things down below.
Replace an array segment in place
JavaScript: splice returns removed items and inserts replacements at the chosen position.
JavaScript✓ Tested
Replace one collection element
JavaScript: Update an existing element at a known valid index.
JavaScript✓ Tested
Require two conditions to be true
JavaScript: Combine a lower and an upper bound to check whether a value is in range.
JavaScript✓ Tested
Resolve a relative URL against a base
JavaScript: A trailing slash makes the final base path component a directory.
JavaScript✓ Tested
Reverse a copy while preserving the original
JavaScript: Copy before reverse because reverse mutates the array it receives.
JavaScript✓ Tested
Run cleanup after a promise settles
JavaScript: finally runs after success or failure and normally preserves the original outcome.
JavaScript✓ Tested
Run dependent async steps in order
JavaScript: Await one result before using it as the input of the next calculation.
JavaScript✓ Tested
Run your first program
JavaScript: Start with a complete program that prints one line. Follow the run instructions below.
JavaScript✓ Tested
Separate a first item from the remaining items
JavaScript: Array destructuring and a rest element produce named pieces of a sequence.
JavaScript✓ Tested
Serialize an object
Turn a JavaScript object into JSON text.
JavaScript✓ Tested
Sort numbers numerically
Supply a numeric comparator instead of JavaScript string sorting.
JavaScript✓ Tested
Sort timestamp strings by their parsed instants
JavaScript: Compare epoch values explicitly when date strings may contain different offsets.
JavaScript✓ Tested