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You Are Here: Home/Template Literals In JavaScript

Template Literals In JavaScript

May 17, 2020

Table Of Contents

    Template literals are string literals that allow embedding an expression. It is possible to use string interpolation and multi-line string features with them.

    Replacing placeholders with values inside of a string literal is called string interpolation.

    In JavaScript, there are 3 ways of defining a string:

    // Single quote
    const single = 'I am a string';
    // Double quotes
    const double = "I am a string";
    // Backticks
    const backticks = `I am a string`;

    You are probably familiar with those 2 at the top but have you seen string in backticks `` before?

    Template Literals

    Template literals are enclosed by the backticks ``.

    They can contain placeholders, which are enclosed by the dollar sign along with curly braces ${...}.

    The expressions, that are passed as placeholders are evaluated during the run-time and their result is inserted into the string.


    Placeholders can contain basically everything:

    • numbers ${10}
    • operations ${10 + 10}
    • variables ${variable}
    • function calls ${example(10)}

    Example using addition operation:

    const string = `The result is: ${10 + 10}`;
    console.log(string); // Prints "The result is: 20"

    Example using function call:

    const evaluate = (nr1, nr2) => nr1 + nr2;
    const string = `The result is: ${evaluate(10, 10)}`;
    console.log(string); // Prints "The result is: 20"

    The placeholder expression result is implicitly converted to a string:

    const number = 10;
    // Variable "number" is evaluated to number "3.5"
    // Afterwards, "3.5" is converted into a string
    const string = `The result is: ${number}`;
    console.log(string); // Prints "The result is: 10"

    Important note: if the placeholder contains an object, method toString is applied to it:

    const numbers = [10, 20, 30];
    // Method "numbers.toString()" is called
    const string = `The result is: ${numbers}`;
    console.log(string); // Prints "The result is: 10,20,30"

    Escaping Placeholders

    In the template strings, placeholder expressions have special meanings, so it's not possible to use the following pattern without escaping `I love ${apple}`.

    Let's try:

    // ReferenceError: apple is not defined
    const string = `I love ${apple}`;

    In order to tell the interpreter to skip ${apple} evaluation, you should use a backslash before the placeholder, like this: \${apple}:

    const string = `I love \${apple}`;
    console.log(string); // Prints "I love ${apple}"

    Multi-Line Strings

    Before introducing template literal feature, JavaScript provided 3 ways of defining multi-line strings:

    • Escaping newlines
    • Concatenating strings
    • Creating an array of strings
    // Escaping newlines
    "I am \
    multi-line \
    // Concatenating strings
    "I am " +
    "multi-line " +
    // Array of strings
      "I am ",
      "multi-line ",

    Those ways look ugly and contain some unnecessary markup. They can easily be rewritten using template literals:

    `I am 

    Nesting Placeholders

    Nesting placeholders sometimes is the best and easiest method to get things done.

    You are allowed to use single/double quotes or backticks inside of the placeholder:

    const number10 = 10;
    const number20 = 20;
    const showNumber10 = true;
    const showNumber20 = false;
    const string = `
      The result is: ${showNumber10 ? number10 : showNumber20 ? number20 : ``}
    console.log(string); // Prints: "The result is 10"

    Tagged Templates

    Tagged templates is a more advanced form of template literals.

    Tags allow you to parse template literals with a function. The first argument of a tag function contains an array of string values. The remaining arguments are related to the expressions.

    The tag function executes provided logic on the passed string and returns manipulated string:

    const age = 18;
    function cookieCounter(strings, personExp, ageExp) {
        These variables won't be used later on
        They are present to show how you can access the input
      const str0 = strings[0]; // "The person is "
      const str1 = strings[1]; // " years old"
      let cookiesNumber = 0;
      if (age >= 18){
        cookiesNumber = 5;
      return `Allowed number of cookies: ${cookiesNumber}`;
    const result = cookieCounter`The person is ${age} years old`;
    console.log(result); // Prints "Allowed number of cookies: 5"

    Important note: the first argument strings in the function above contains raw method which can be used to access raw input string:

    const age = 18;
    function cookieCounter(strings, personExp, ageExp) {
      // Prints ["The person is ", " years old"]
    cookieCounter`The person is ${age} years old`;


    Template literals allow us to put values inside of a string in a very readable and concise way and allow a clumsy concatenation approach.

    • Template literal is wrapped by backticks ``
    • Template literal can be given a value by putting it into the placeholder ${...}
    • Placeholder can be escaped by using backslash \${apple}
    • Template literals are great to create a multi-line string
    • Template literals can be nested
    • Template literals can be tagged
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