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ES6 Template literals / strings

Nov 03 2020

Every year, as the year end approaches, I try to refresh my knowledge of technical topics I am working on, and the ones I love. This year too, as November began, so did my refresher journey. I started by going through the JavaScript concepts.

And, I came across template literals concept. As a React developer, I have been using this feature extensively and this is certainly one of the most useful features to come in ES6.

It is used for string substitution and for creating multiline strings.

On further read, I found something called as tagged templates. As I never read it before, this intrigued me and I dig deeper to understand its syntax and usage.

Tagged Templates

Tagged templates are basically a special type of function call where function name is placed before the template string.

Code Example:

function showOrderDetails(stringVals, ...values) {
  /**
  * stringVals contains all the strings in array form,
  * the second onwards parameters of this function contain
  * all the individual string interpolated values
  * and we are gathering them in 'values' using rest operator.
  */
  let resultStr = '';
  for (let i = 0; i < stringVals.length; i++) {
    if (i > 0) {
      if (typeof values[i - 1] === "number") {
        resultStr += `$${values[i-1].toFixed(2)}`;
      } else {
        resultStr += values[i-1]
      }
    }
    resultStr += stringVals[i]
  }
  return resultStr;
}

let name = "Anu";
let price = 2500;

showOrderDetails`Congratulations ${name}! Your order for ${price} has been successfully placed`

/** output ->
Congratulations Anu! Your order for $2500.00 has been successfully placed
*/

Usage

Tagged template is such a powerful concept, and can be used for a wide range of scenarios, like formatting, localization, automatic escaping of any interpolated variables, etc.. Checkout the references section to explore more about template literals and tagged templates.

References: