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  3. Append Characters or Words to a String in JavaScript or Node.js

Append Characters or Words to a String in JavaScript or Node.js

Working with strings you’re running into typical use-cases. One of them is to append characters or words to an existing string. For example, you may want to check whether a view template file exists on your local hard disk. For that check you need the filename with extension. Your method checking for file existence may append the missing file extension if not provided.

This tutorial shows you how to add a suffix to the tail of a string in JavaScript.

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Add a Suffix to the End of a String in JavaScript

JavaScript comes with built-in string handling. You can append a string to an existing string value using the + operator:

const value = 'Future '  
const appended = value + 'Studio'  
// 'Future Studio'

Please notice that using the + operator when the first argument is a string, JavaScript creates a string from the second parameter as well. In case the second argument is undefined or null you’ll end up adding the 'undefined' or 'null' strings to the first one:

const value = 'Future '

const appendedUndefined = value + undefined  
// 'Future undefined'

const appendedNull = value + null  
// 'Future null'

Another approach are template strings. Template literals are strings composed using backtick `` characters as the delimiter. You’re using a template syntax${}` within the template string to inject values:

const studio = 'Studio'

const appended = `Future ${studio}`  
// 'Future Studio'

const appendedUndefined = `Future ${undefined}`  
// 'Future undefined'

const appendedNull = `Future ${null}`  
// 'Future null'

Use the @supercharge/strings Package

I’m the maintainer of the @supercharge/strings package providing convenient string utilities. The @supercharge/strings package comes with a handy Str#append method.

The append method adds a given text to the end of a string. It won’t append undefined or null values and leaves the source string “as is” instead. You can also chain further methods for more string customizations:

import { Str } from '@supercharge/string'

Str('Future').append().get()  
// 'Future'

Str('Future').append(null).get()  
// 'Future'

Str('Future ').append('Studio').get()  
// 'Future Studio'

Str('Future').append(' ').append('Studio').get()  
// 'Future Studio'

Enjoy suffixing strings!

Marcus Pöhls

Marcus is a fullstack JS developer. He’s passionate about the hapi framework for Node.js and loves to build web apps and APIs. Creator of Futureflix and the “learn hapi” learning path.

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