Tiny Typescript string template compiler

compileTemplate.ts

// makes use of tagged template literals
const compileTemplate = (strings: TemplateStringsArray, ...expr: string[]) => {
  return (replacements: Record<string, any>) => {
    // convert ${'whatever'} instances to array of values
    const values = expr.map(key => replacements[key] ?? key);
    // rebuild string with replaced values
    return strings.reduce((result, part, i) => result + part + (values[i] ?? ''), '');
  }
}
    
// Usage

const template = compileTemplate`this is a ${'thing'}`;
const formatted = template({ thing: 'pen' });
// formatted === 'this is a pen'