Functions and Scope

Parameters and Return

Pass several arguments and use the returned value.

params-return A function can take several parameters and return one value. The returned value is just a number here, so it can feed into more expressions.

Parameters and Return

w
params_return.js
Replay: real traced execution (multi-file project)
function rectangle(width, height) {
  return width * height;
}

const w = 4;
const h = 3;
const area = rectangle(w, h);

console.log("area=" + area);
console.log("doubled=" + (area * 2));

function rectangle(width, height) {
  return width * height;
}

const w = 2;
const h = 3;
const area = rectangle(w, h);

console.log("area=" + area);
console.log("doubled=" + (area * 2));

function rectangle(width, height) {
  return width * height;
}

const w = 6;
const h = 3;
const area = rectangle(w, h);

console.log("area=" + area);
console.log("doubled=" + (area * 2));

  1. w ← 4, h ← 3

    2  return width * height;3}45const w→ 4 = 4; //@w=2, 66const h→ 3 = 3;7const area = rectangle(w4, h3);

  2. function rectangle(width, height)

    1function rectangle(width4, height3) {2  return width * height3;3}

  3. area ← 12

    5const w = 4; //@w=2, 66const h = 3;7const area→ 12 = rectangle(w4, h3);89console.log("area=" + area12);10console.log("doubled=" + (area→ 12 * 2));
    outputarea=12
doubled=24

  1. w ← 2, h ← 3

    2  return width * height;3}45const w→ 2 = 2;6const h→ 3 = 3;7const area = rectangle(w2, h3);

  2. function rectangle(width, height)

    1function rectangle(width2, height3) {2  return width * height3;3}

  3. area ← 6

    5const w = 2;6const h = 3;7const area→ 6 = rectangle(w2, h3);89console.log("area=" + area6);10console.log("doubled=" + (area→ 6 * 2));
    outputarea=6
doubled=12

  1. w ← 6, h ← 3

    2  return width * height;3}45const w→ 6 = 6;6const h→ 3 = 3;7const area = rectangle(w6, h3);

  2. function rectangle(width, height)

    1function rectangle(width6, height3) {2  return width * height3;3}

  3. area ← 18

    5const w = 6;6const h = 3;7const area→ 18 = rectangle(w6, h3);89console.log("area=" + area18);10console.log("doubled=" + (area→ 18 * 2));
    outputarea=18
doubled=36