Native Template Expression Parsing

parseExpressions.js

function parseExpressions(data, template) {
  function stringify(strings, ...values) {
    function isObject(obj) {
      return obj !== null && typeof obj === "object";
    }

    const toDisplayString = (value) =>
      value == null
        ? ""
        : isObject(value)
        ? JSON.stringify(value, null, 2)
        : String(value);

    let index = 0;
    return strings
      .map((s) => (s ? s + toDisplayString(values[index++]) : ""))
      .join("");
  }

  if (data !== undefined) {
    return new Function(
      "data",
      "stringify",
      "with(data) {return stringify`" + template + "`}"
    )(data, stringify);
  }
}

usage.js

let data = {
  name: {
    first: "John",
    last: "Doe"
  }
}
let template = "<span>${name.first} ${name.last}</span>"

parseExpressions(data, template); // => <span>John Doe</span>