Last updated about 1 week ago

Javascript

• MDN Docs

• Comprehensive Tutorial

• A good breakdown of function terminology

• Microsoft Developer Javascript Resources

Notes

• Make a dynamic chain of promises

  Use

  arr.reduce((c, d) => c.then(() => fn(d)), Promise.resolve()).catch(error);

  to convert

  const arr = [d1, d2, d3, ..., dn];
  const fn = async (d) => { /* returns a promise */ };

  into

  Promise.resolve().then(() => fn(d1)).then(() => fn(d2)).then(() => fn(d3))...then(() => fn(dn)).catch(error)

  • In newer versions:

    for (const d of arr) await fn(d);

• Convert string to num shorthand

  const numStr = "1.23";
  const numVal = +numStr;

• Get integer part of a fraction (like Math.floor)

  const fraction = 1.234;
  const intPart = ~~fraction; // 1
  const intPart2 = fraction << 0; // 1

  The ~ operator is 2’s complement