Tagged template unindent helper

unindent.ts

export function unindent(template: TemplateStringsArray, ...args: any[]): string {
  let numSpaces = 999;
  for (const part of template) {
    for (const indentation of part.match(/\n +/g) || []) {
      numSpaces = Math.min(numSpaces, indentation.length - 1);
    }
  }

  const spaces = new RegExp('\n' + ' '.repeat(numSpaces < 999 ? numSpaces : 0), 'g');
  return template
    .map((part, i) => (i ? args[i - 1] : '') + part.replace(spaces, '\n'))
    .join('')
    .replace(/^\n|\n$/g, '');
}

​unindent-test.ts

import { unindent } from './unindent';

const a = unindent`
  Helper to remove
    indentation
  from tagged text
`;

console.assert(a === 'Helper to remove\n  indentation\nfrom tagged text', 'a');


const b = unindent`
    The smallest
  indentation is used
    for all lines
`;

console.assert(b === '  The smallest\nindentation is used\n  for all lines', 'b');


const c = unindent`
    Variables
      are inserted (${1 + 2})
    as expected
`;

console.assert(c === 'Variables\n  are inserted (3)\nas expected', 'c');


const d = unindent`

    Extra leading or trailing
    newlines are preserved

`;

console.assert(d === '\nExtra leading or trailing\nnewlines are preserved\n', 'd');

​unindent.js

export function unindent(template, ...args) {
  let numSpaces = 999;
  for (const part of template) {
    for (const indentation of part.match(/\n +/g) || []) {
      numSpaces = Math.min(numSpaces, indentation.length - 1);
    }
  }

  const spaces = ' '.repeat(numSpaces < 999 ? numSpaces : 0);
  const spacesRegex = new RegExp('\n' + spaces, 'g');
  return template
    .map((part, i) => (i ? args[i - 1] : '') + part.replace(spacesRegex, '\n'))
    .join('')
    .replace(/^\n|\n$/g, '');
}

​unindent.min.js

export function unindent(n,...e){let t=999;for(const e of n)for(const n of e.match(/\n +/g)||[])t=Math.min(t,n.length-1);const o=" ".repeat(t<999?t:0),r=new RegExp("\n"+o,"g");return n.map((n,t)=>(t?e[t-1]:"")+n.replace(r,"\n")).join("").replace(/^\n|\n$/g,"")}