Camel case vs snake case is a common question among developers when choosing a naming convention for their code. This guide will help you understand the differences between these two popular naming conventions, their typical uses, and how to choose the right one for your project.
Understanding Naming Conventions
Choosing the right naming convention is crucial for code readability and maintainability. Here, we will explore the most common naming conventions: camelCase, snake_case, PascalCase, kebab-case, and SCREAMING_SNAKE_CASE.
camelCase
camelCase is a naming convention where the first word is in lowercase and each subsequent word starts with an uppercase letter, with no spaces or underscores between words. For example, userName. This convention is widely used in JavaScript, Java, and C# for variables and functions.
snake_case
snake_case is a naming convention where all letters are in lowercase and words are separated by underscores. For example, user_name. This convention is commonly used in Python and Ruby for variables and functions.
Other Conventions
- PascalCase / UpperCamelCase: Similar to camelCase, but the first word also starts with an uppercase letter. For example,
UserName. This is often used for classes and types in languages like Java and C#. - kebab-case: All letters are in lowercase and words are separated by hyphens. For example,
user-name. This is commonly used in CSS classes, URL slugs, and npm package names. - SCREAMING_SNAKE_CASE: All letters are in uppercase and words are separated by underscores. For example,
MAX_SIZE. This is typically used for constants in many programming languages.
Comparison of Naming Conventions
| Convention | Example | Where it’s used |
|---|---|---|
| camelCase | userName | JavaScript, Java, C# |
| snake_case | user_name | Python, Ruby |
| PascalCase | UserName | Java, C# (classes/types) |
| kebab-case | user-name | CSS, URLs, npm package names |
| SCREAMING_SNAKE_CASE | MAX_SIZE | Constants in many languages |
It’s important to note that the choice of naming convention is more about consistency and convention rather than correctness. Different languages and frameworks have their own conventions, and adhering to them can improve the readability of your code. For JSON keys, there is no strict rule, but they are commonly written in camelCase or snake_case. For more on JSON, check out our JSON formatter and common JSON errors guide.
Conventions by language and context
| Language/Context | Preferred Convention |
|---|---|
| JavaScript | camelCase |
| Python | snake_case |
| Go (exported) | PascalCase |
| Rust | snake_case |
| SQL column names | snake_case |
| HTTP header names | PascalCase (e.g., Content-Type) |
| CSS classes | kebab-case (e.g., my-class) |
| URL slugs | kebab-case (e.g., my-page) |
Database and API naming
When designing APIs and databases, choosing a consistent naming convention is crucial for maintainability and to avoid unnecessary complexity. One common issue arises when an API returns data in snake_case to a frontend that expects camelCase. This mismatch forces the introduction of a mapping layer, which can introduce bugs and increase the complexity of your codebase.
For example, consider an API that returns a JSON object with keys like user_id and created_at. If your frontend is written in JavaScript, which typically uses camelCase, you will need to convert these keys to userId and createdAt. This conversion can be handled manually or through automated tools, but it adds an extra step to your data handling process.
To avoid this, it is advisable to pick one convention per boundary. If your API uses snake_case, your frontend should also use snake_case to maintain consistency. Alternatively, if your team prefers camelCase for the frontend, you might consider converting the API responses to camelCase before they are sent to the client. This approach minimizes the need for mapping and reduces the likelihood of bugs related to inconsistent naming conventions.
Consistency in naming conventions across your entire stack, from the database to the frontend, leads to cleaner, more readable code and simplifies the development process. It also makes it easier for new team members to understand and contribute to the codebase.
Using QuikConsole’s Free Tool
To help you maintain consistency in your naming conventions, QuikConsole offers a free, browser-based tool that can assist in converting between different naming conventions. This tool runs entirely in your browser, and nothing you paste is ever uploaded. Try it out here.
How to choose
When deciding between camelCase and snake_case, consider the following factors:
- Language’s standard library / style guide: Most programming languages have a preferred naming convention. For example, JavaScript and Java typically use camelCase, while Python and C++ often use snake_case. Following the language’s standard library or official style guide ensures consistency within your codebase.
- Match the surrounding codebase: If you are working on an existing project, it is important to maintain consistency with the existing naming conventions. This makes the code easier to read and maintain for all developers involved.
- Pick one and stay consistent: Once you have chosen a naming convention, stick with it throughout your project. Inconsistent naming conventions can lead to confusion and make the code harder to understand.
Here are some examples of how different languages and frameworks prefer one style over the other:
| Language / Framework | Preferred Convention |
|---|---|
| JavaScript | camelCase |
| Python | snake_case |
| Java | camelCase |
| C++ | snake_case |
| Ruby | snake_case |
Converting between cases
Converting between camelCase and snake_case involves the following steps:
- Split on word boundaries: Identify the word boundaries in the original string. In camelCase, this is typically where a lowercase letter is followed by an uppercase letter. In snake_case, the word boundaries are indicated by underscores.
- Case changes: Change the case of the letters as needed. For example, in camelCase, the first word is lowercase, and each subsequent word starts with an uppercase letter. In snake_case, all letters are typically lowercase.
- Rejoin in the target style: Combine the words using the target convention’s separators. For camelCase, no separators are used. For snake_case, underscores are used to separate words.
Here is an example of converting between the two styles:
Original string: thisIsASampleString Conversion to snake_case: 1. Split on word boundaries: this, Is, A, Sample, String 2. Change case: this, is, a, sample, string 3. Rejoin: this_is_a_sample_string Conversion to camelCase: 1. Split on word boundaries: this_is_a_sample_string 2. Change case: this, is, a, sample, string 3. Rejoin: thisIsASampleString
It is important to note that converting between cases can be a common source of bugs, especially when dealing with APIs that return data in one format and a frontend that expects another. For example, if an API returns data in snake_case and the frontend is expecting camelCase, you may need to convert the keys of the returned objects to match the expected format.
Frequently asked questions
What is the difference between camelCase and snake_case?
camelCase uses no spaces or underscores and starts with a lowercase letter (e.g., userName), while snake_case uses all lowercase letters and underscores to separate words (e.g., user_name).
Which languages use camelCase?
JavaScript, Java, and C# typically use camelCase for variables and functions.
Which languages use snake_case?
Python and Ruby typically use snake_case for variables and functions.
What is the convention for constants?
Constants are typically written in SCREAMING_SNAKE_CASE, with all uppercase letters and underscores (e.g., MAX_SIZE).
How do I choose the right naming convention?
The choice depends on the language and framework you are using. It’s important to be consistent and follow the conventions of the language or framework you are working with.