Standard Library Utilities

Padding Strings

Pad a label so short values line up.

pad-strings `padStart` and `padEnd` add characters until a string reaches a chosen length. This is useful for fixed-width labels.

Padding Strings

id
pad_strings.js
Replay: real traced execution (multi-file project)
const id = "7";
const left = id.padStart(3, "0");
const right = id.padEnd(4, ".");

console.log("id=" + id);
console.log("left=" + left);
console.log("right=" + right);

const id = "42";
const left = id.padStart(3, "0");
const right = id.padEnd(4, ".");

console.log("id=" + id);
console.log("left=" + left);
console.log("right=" + right);

const id = "305";
const left = id.padStart(3, "0");
const right = id.padEnd(4, ".");

console.log("id=" + id);
console.log("left=" + left);
console.log("right=" + right);

  1. id ← 7, left ← 007, right ← 7...

    1const id→ 7 = "7"; //@id="42", "305"2const left→ 007 = id7.padStart(3, "0");3const right→ 7... = id7.padEnd(4, ".");45console.log("id=" + id7);6console.log("left=" + left007);7console.log("right=" + right7...);
    outputid=7
left=007
right=7...

  1. id ← 42, left ← 042, right ← 42..

    1const id→ 42 = "42";2const left→ 042 = id42.padStart(3, "0");3const right→ 42.. = id42.padEnd(4, ".");45console.log("id=" + id42);6console.log("left=" + left042);7console.log("right=" + right42..);
    outputid=42
left=042
right=42..

  1. id ← 305, left ← 305, right ← 305.

    1const id→ 305 = "305";2const left→ 305 = id305.padStart(3, "0");3const right→ 305. = id305.padEnd(4, ".");45console.log("id=" + id305);6console.log("left=" + left305);7console.log("right=" + right305.);
    outputid=305
left=305
right=305.