4 Ways to Combine Strings in JavaScript
Tags: javascript, beginners, codenewbie, webdev
Published: 2020-07-28 15:00:59

![Code snippets of the 4 ways to combine strings using template strings, join, concat, and plus operator](https://dev-to-uploads.s3.amazonaws.com/i/zhxgslvcz9k8t039zh3j.png)

Here are 4 ways to combine strings in JavaScript. My favorite way is using Template Strings. Why? Because it’s more readable, no backslash to escape quotes, no awkward empty space separator, and no more messy plus operators 👏

```js
const icon = '👋';

// Template Strings
`hi ${icon}`;

// join() Method
['hi', icon].join(' ');

// Concat() Method
''.concat('hi ', icon);

// + Operator
'hi ' + icon;

// RESULT
// hi 👋
```

<!-- Let's dive a bit deeper to see all these different ways to combine or concatenate our string. -->

## 1. Template Strings

If you come from another language, such as Ruby, you will be familiar with the term **string interpolation**. That's exactly what template strings is trying to achieve. It's a simple way to include expressions in your string creation which is readable and concise.

```javascript
const name = 'samantha';
const country = '🇨🇦';
```

### Problem of Missing space in String concatenation

Before template strings, this would be the result of my string 😫

```javascript
"Hi, I'm " + name + "and I'm from " + country;
```

☝️ Did you catch my mistake? I'm missing a space 😫. And that's a super common issue when concatenating strings.

```javascript
// Hi, I'm samanthaand I'm from 🇨🇦
```

### Resolved with Template Strings

With template strings, this is resolved. You write exactly how you want your string to appear. So it's very easy to spot if a space is missing. Super readable now, yay! 👏

```javascript
`Hi, I'm ${name} and I'm from ${country}`;
```

## 2. join()

The `join` method combines the elements of an array and returns a string. Because it's working with array, it's very handy if you want to add additional strings.

```javascript
const array = ['My handles are'];
const handles = [instagram, twitter, tiktok].join(', '); // @samanthaming, @samantha_ming, @samanthaming

array.push(handles); // ['My handles are', '@samanthaming, @samantha_ming, @samanthaming']

array.join(' '); 

// My handles are @samanthaming, @samantha_ming, @samanthaming
```

### Customize Separator

The great thing about `join` is that you can customize how your array elements get combined. You can do this by passing a separator in its parameter.

```javascript
const array = ['My handles are '];
const handles = [instagram, twitter, tiktok].join(', '); // @samanthaming, @samantha_ming, @samanthaming

array.push(handles);

array.join('');

// My handles are @samanthaming, @samantha_ming, @samanthaming
```

## 3. concat()

With `concat`, you can create a new string by calling the method on a string.

```javascript
const instagram = '@samanthaming';
const twitter = '@samantha_ming';
const tiktok = '@samanthaming';

'My handles are '.concat(instagram, ', ', twitter', ', tiktok);

// My handles are @samanthaming, @samantha_ming, @samanthaming
```

### Combining String with Array

You can also use `concat` to combine a string with an array. When I pass an array argument, it will automatically convert the array items into a string separated by a comma `,`.

```javascript
const array = [instagram, twitter, tiktok];

'My handles are '.concat(array);

// My handles are @samanthaming,@samantha_ming,@samanthaming
```

If you want it formatted better, we can use `join` to customize our separator.

```javascript
const array = [instagram, twitter, tiktok].join(', ');

'My handles are '.concat(array);
// My handles are @samanthaming, @samantha_ming, @samanthaming
```

## 4. Plus Operator (+)

One interesting thing about using the `+` operator when combining strings. You can use to create a new string or you can mutate an existing string by appending to it.

### Non-Mutative

Here we are using `+` to create a brand new string.

```javascript
const instagram = '@samanthaming';
const twitter = '@samantha_ming';
const tiktok = '@samanthaming';

const newString = 'My handles are ' + instagram + twitter + tiktok;
```

### Mutative

We can also append it to an existing string using `+=`. So if for some reason, you need a mutative approach, this might be an option for you.

```javascript
let string = 'My handles are ';

string += instagram + twitter;

// My handles are @samanthaming@samantha_ming
```

OH darn 😱 Forgot the space again. SEE! It's so easy to miss a space when concatenating strings.

```javascript
string += instagram + ', ' + twitter + ', ' + tiktok;

// My handles are @samanthaming, @samantha_ming, @samanthaming
```

That feels so messy still, let's throw `join` in there!

```javascript
string += [instagram, twitter, tiktok].join(', ');

// My handles are @samanthaming, @samantha_ming, @samanthaming
```

## Escaping Characters in Strings

When you have special characters in your string, you will need to first escape these characters when combining. Let's look through a few scenarios and see how we can escape them 💪

### Escape Single Quotes or Apostrophes (')

When creating a string you can use single or double quotes. Knowing this knowledge, when you have a single quote in your string, a very simple solution is to use the opposite to create the string.

```javascript
const happy = 🙂;

["I'm ", happy].join(' ');

''.concat("I'm ", happy);

"I'm " + happy;

// RESULT
// I'm 🙂
```

Of course, you can also use the backslash, `\` , to escape characters. But I find it a bit difficult to read, so I don't often do it this way.

```javascript
const happy = 🙂;

['I\'m ', happy].join(' ');

''.concat('I\'m ', happy);

'I\'m ' + happy;

// RESULT
// I'm 🙂
```

_Because Template strings is using backtick, this scenario doesn't apply to it 👍_

### Escape Double Quotes (")

Similar to escaping single quotes, we can use the same technique of using the opposite. So for escaping double quotes, we will use single quotes.

```javascript
const flag = '🇨🇦';

['Canada "', flag, '"'].join(' ');

''.concat('Canada "', flag, '"');

'Canada "' + flag + '"';

// RESULT
// Canada "🇨🇦"
```

And yes, can also use the backslash escape character.

```javascript
const flag = '🇨🇦';

['Canada "', flag, '"'].join(' ');

''.concat('Canada "', flag, '"');

'Canada "' + flag + '"';

// RESULT
// Canada "🇨🇦"
```

_Because Template strings is using backtick, this scenario doesn't apply to it 👍_

### Escape backtick

Because Template strings is using backticks to create its string, when do want to output that character, we have to escape it using backslash.

```javascript
const flag = '🇨🇦';

`Use backtick \`\` to create a template string`;

// RESULT
// Use backtick `` to create a template string
```

_Because the other string creations are not using backtick, this scenario doesn't apply to them 👍_

## Which way to use?

I showed a few examples of using the different ways of concatenating strings. Which way is better all depends on the situation. When it comes to stylistic preference, I like to follow Airbnb Style guide.

> When programmatically building up strings, use template strings instead of concatenation. eslint: [prefer-template template-curly-spacing](https://eslint.org/docs/rules/prefer-template.html)

So template strings for the win! 👑

### Why the other ways still matter?

It's still important to know the other ways as well. Why? Because not every code base will follow this rule or you might be dealing with a legacy code base. As a developer, we need to be able to adapt and understand whatever environment we're thrown in. We're there to problem solve not complain how old the tech is lol 😂 Unless that complaining is paired with tangible action to improve. Then we got progress 👏

## Browser Support

| Browser           | Template String | join        | concat    | +         |
| ----------------- | :-------------: | ----------- | --------- | --------- |
| Internet Explorer |       ❌        | ✅ _IE 5.5_ | ✅ _IE 4_ | ✅ _IE 3_ |
| Edge              |       ✅        | ✅          | ✅        | ✅        |
| Chrome            |       ✅        | ✅          | ✅        | ✅        |
| Firefox           |       ✅        | ✅          | ✅        | ✅        |
| Safari            |       ✅        | ✅          | ✅        | ✅        |

## Resources

- [MDN Template Literals](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals)
- [MDN: concat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/concat)
- [MDN: join](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join)
- [MDN: +](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Addition)
- [Stack Overflow: Most efficient way to concatenate strings in JavaScript?](https://stackoverflow.com/questions/16696632/most-efficient-way-to-concatenate-strings-in-javascript)
- [3 Ways to Concatenate Strings](https://masteringjs.io/tutorials/fundamentals/string-concat)
- [Digital Ocean: How To Work with Strings in JavaScript](https://www.digitalocean.com/community/tutorials/how-to-work-with-strings-in-javascript)
- [Airbnb Style Guide](https://github.com/airbnb/javascript#es6-template-literals)
- [ESLint: prefer-template](https://eslint.org/docs/rules/prefer-template.html)
- [SamanthaMing: How to Create Multi-Line String with Template Literals](https://www.samanthaming.com/tidbits/58-multi-line-strings-with-template-literals/)
- [SamanthaMing: join](articles/basics/array-join.md)

---

**Thanks for reading ❤**
To find more code tidbits, please visit [samanthaming.com](https://www.samanthaming.com/)

<table>
  <tbody>
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      </td>
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