JavaScript version
toFullHexColor.js
const toFullHexColor = (color) =>
`#${(color.startsWith('#') ? color.slice(1) : color)
.split('')
.map((c) => `${c}${c}`)
.join('')}`;
TypeScript version
toFullHexColor.ts
const toFullHexColor = (color: string): string =>
`#${(color.startsWith('#') ? color.slice(1) : color)
.split('')
.map((c) => `${c}${c}`)
.join('')}`;
Examples
examples.js
toFullHexColor('123'); // '#112233'
toFullHexColor('#123'); // '#112233'
toFullHexColor('#abc'); // '#aabbcc'