Discover the JavaScript String & How it Works

One of the most common data types programmers use in software development is string values. While this is true in any programming language, strings often have different characteristics and behavior across languages. For example, in JavaScript, strings are primitive data types, while in Java, however, strings are class objects.

Throughout this post, you will learn about the JavaScript string object and how to use it. You will also learn to understand its behavior and syntax through code examples and explanations. There will also be some video content to help you solidify your understanding of the core concepts. Below are some links to help with navigating this post.

• How to Declare a String in JavaScript
• JavaScript String Example
• Next Steps on Incorporating JavaScript Strings Into Your Software

Let’s get started.

What is a JavaScript String?

JavaScript is an object-oriented programming language, meaning almost everything in JavaScript is an object. Many of those objects have a datatype that affects how they can be used in your software development. However, JavaScript strings are considered a primitive datatype, which means they are not objects.

This fact is crucial because primitive datatypes do not have methods or properties. However, some objects and classes offer methods that can be used. With that in mind, it will be valuable to your programming efforts to understand how they work and how you can interact with them. The next video briefly explains the JavaScript string and how it works.

Next, let's discuss the syntax of string declarations and discover ways you can use them.

How to Declare a String in JavaScript

There is only one standard syntax for declaring a new string, but there are slightly different syntaxes you can use. So, to clarify, let’s discuss that next with some examples of each.

Generally, quotes indicate that a data value is a string, which can be seen in the code snippet below.

 
let greeting = 'Hello';
let greeting = "Doctor";

The example above shows the syntax for declaring a string using a single quote and the syntax for declaring with a double quote. The process is essentially the same either way. However, there are other ways to create strings. 

Next up is the string template literal, which uses the backtick instead of quotes to declare a string. 

String Template Literal

The great thing about this approach is that it makes string declaration more dynamic, especially when paired with interpolation. You can use interpolation with template literals to insert values into strings dynamically.

First, let’s look at the syntax for using a backtick to create a simple string value.

 
let name = `The Doctor`;

 
let name = `The Doctor`;
let message = `Hello, I'm ${name}.`;/*${interpVar}*/

With template literals and interpolation, strings become even more powerful and robust. Template literals also make it easy to nest quotes within a string, and this is useful when you need to quote someone. For example, in video game development, this is a very common practice.

You can see this process in the example code snippet below.

 
let message = `"I'm The Doctor." She said.`;

Next, let's discuss how you will often use strings in your software development.

String Uses

As discussed above, JavaScript strings are primitive data types and have no built-in methods. Primitive data types are meant to be simplistic but allow developers to create dynamic, robust, and powerful data structures.

Strings are most often used to record input data from the user or display information to the user based on some condition(s). An example of this would be showing a message to a user after logging into your software. When a user attempts to log in, you may send a message indicating if the lo login was a success or not.

Moreover, you will likely be making a string comparison for login validation, such as confirming a correctly entered username. The fun, however, does not stop there; you may need to convert a non-string value into a string for any number of reasons.

Next, let’s look at how you can convert other data types into strings.

String Conversions

Converting other data types into strings will prove helpful for many of your software development needs. As discussed above, there are many different reasons to use strings and just as many ways to convert them for displaying or validating values. In addition, converting other data types into strings can help with validation, security checks, etc.

Using a concatenation process, you can essentially add a string to a value, and in most cases, it converts the added value into a string. In most cases, you may see this done with an empty string; the code snippet below shows that process.

 
let age= 25;
let ageStr = '' + age;
console.log(ageStr);

The above process outlines converting a number value into a string value. Next, let’s look at some examples of the JavaScript String used in various ways.

JavaScript String Example

Now that you’ve learned about the syntax of string declaration and discovered some ways to convert data types into strings. This section will cover examples of different string values for various data types. You’ll also see how to perform conversions, comparisons, access string characters, and preformat strings for displaying data.

String Values

No matter what kind of data you find yourself working with, string values are still strings. However, there are times when you may expect a value to be something other than a string, and this is not always the case.

For example, when working with objects, the way data is saved slightly different. This is because the keys of objects are always returned as strings, no matter what type of value you use to create them. Let’s look at a code example of a JavaScript object below to clarify this.

 
const doctorWho = {
  image: "doctorWho.jpg",
  name: "The Doctor",
  age: 1204,
  species: "Timelord",
  origin: "Gallifrey",
  region: `Kasterborous`
};

The above object has multiple keys, and the most common practice is to use string values for creating key names. However, sometimes numbers are used to make key names, although less common. In that case, you may expect a numeric value, but the truth is object key values are always returned as strings.

 
console.log(Object.keys(doctorWho));

This means that accessing this object's keys will always return a string even if the value is a number. These types of discrepancies can cause unexpected errors in your software.

Special characters are reserved for string formatting and more. As a result, you will need to escape them when used to ensure your string values are what you expect. For example, if you do not correctly escape nested quotes, the string will end prematurely and cause errors. 

Let’s look at an example of how to do this in the code snippet below.

 
let introduction = 'I\'m The Doctor!';

String Conversions and Comparisons

Understanding how to convert and even compare string values will be very helpful and allow you more robust ways to use strings. The most common way to convert values to a string is to use the .toString() method. This method takes a provided value and returns it as a string value.

 
let age = 904;
let ageStr = age.toString();

The above line of code does what you would expect; it changes the age value, which is entered as a number, into a string. This can make it easier to work with non-string values for various reasons.

Comparing strings is also a very beneficial practice that you may need to use. For example, in the case of game development, you might use string comparisons to confirm players and scores. Another example would be ensuring that a player is already in the game, avoiding duplicate entries.

 
if(currPlayer == newPlayer){
    console.log(“sorry that player already exists”)
}

The code above shows how you could implement a string comparison, assuming the values in both variables are strings. It will look at both strings and check first that they are both strings, then compare their values. This is useful for ensuring unique usernames for your software, helpful no matter what kind of developer you are.

String comparisons are based on the numerical value of the string characters within the strings. The comparison process is case-sensitive; uppercase and lowercase letters have different values. 

Accessing String Characters

In JavaScript, strings are treated as a collection of characters similar to arrays; this makes it easy to identify specific characters within a string. This process is simple and highly beneficial for many different purposes. Examples of popular uses are security, performance, data validation, etc. 

To access a string's characters, you will need to use the array-like notation, which uses the square brackets to target the characters you want. First, let’s look at the process for accessing individual string characters and how to utilize it in your code.

 
let introduction = "The Doctor";
console.log(introduction[0]);

The code above will return a single character from the string base don the index location of the character. In this case, the string character returned will be the character at index zero, the first character.

Next Steps on Incorporating JavaScript Strings Into Your Software

You’ve learned a lot on this subject, and there is still plenty of room to expand and solidify your understanding. In this post, you’ve learned about string declaration syntax, how to declare a string, and some use cases. You’ve also discovered the various easy you can interact with strings, how to convert other data types, and saw some examples of all the above.

As you move forward, there are many ways to build on this knowledge; the best way is to practice. You can use your development environment or one like code pen to create sample projects that let you try using strings in various ways. Finally, the depth and robust nature of strings; there's always something more to learn.