Code Studio

This lab's sandbox. Browsers, Node, and this Code Studio.

This one executes in the sandbox below.

Cheat

• let / const — block scope. var is function scope (avoid).
• === strict equality. == coerces (avoid).
• Array: map, filter, reduce, find, some, every, slice.
• Object: {a: 1}. Access obj.a or obj['a'].
• async: Promise, then, async/await. fetch exists in browsers, not in this sandbox.
• JSON.parse / JSON.stringify for data shapes.
• Template strings: `n=${n}`

Stdlib / core

Math · JSON · Array · String · Number · Date · Object.keys · Map / Set

Pitfalls

• this sandbox has no fetch, no DOM, no require, no parent window.
• Floating point: 0.1 + 0.2 !== 0.3. Use integers for money.
• typeof null === 'object' is a language fossil.

function greet(name) {
  return "hello " + name;
}
print(greet("lab"));