function isTemplateStringsArray(it: unknown): it is TemplateStringsArray;

Checks if the given value is a template strings array, which is an array of strings with an own property named raw that also is an array of strings. This is the type of array provided to tagged template literals for the first argument, and is represented as the type TemplateStringsArray in TypeScript.

This predicate's type is a supertype of the one checked by its more lenient counterpart, isTemplateObject, which only checks if the value is an object with a raw property that is an array of strings.

true if the value is a TemplateStringsArray, false otherwise.

Template Literals

import { isTemplateStringsArray } from "jsr:@nick/is/template-strings-array";

console.log(isTemplateStringsArray(["a", "b", "c"])); // false
console.log(isTemplateStringsArray({ raw: ["a", "b", "c"] })); // false

function print(strings: TemplateStringsArray, ...values: any[]): string;
function print(...vals: unknown[]): string;
function print(...vals: unknown[]): string {
  const [strings, ...values] = vals;
  if (isTemplateStringsArray(strings)) {
    return String.raw(strings, ...values);
  } else {
    return JSON.stringify(vals);
  }
}

print(["a", "b", "c"], 1, 2, 3); // '[["a", "b", "c"], 1, 2, 3]'
print`a${1}b${2}c${3}`; // a1b2c3

A template strings array is an array of strings with an own property named raw that is also an array of strings. This is the type of array provided to tagged template literals for the first argument, and is represented as the type TemplateStringsArray in TypeScript.

Note: while all TemplateStringsArray values are TemplateStringsObjects, not all TemplateStringsObjects are TemplateStringsArrays.

Types

TemplateStringsArray

readonly raw: ReadonlyArray<string>;