Software Development

Why are my functions different colors? A guide to context.

Ever wonder why your functions are yellow in one place and blue in another? This guide demystifies code editor colors, explaining context, scope, and syntax highlighting.

Daniel Carter

A senior software engineer and developer educator passionate about making code more intuitive.

September 11, 20256 min read15 views

You’re in the zone, fingers flying across the keyboard. You write a new function, and your code editor dutifully colors it a familiar, satisfying yellow. A few lines down, you call a built-in browser API, and it pops up in a cool teal. Then you call your own function, and suddenly it’s… light blue? Or maybe just plain white?

If you’ve ever paused and thought, “Wait, why are these colors different? Is something wrong?”—you’re not alone. It’s a question every developer has at some point. The good news is, it’s not a bug. It’s a feature. A very powerful one.

Those shifting colors are your editor’s way of giving you instant, at-a-glance information. They’re a visual language for code context. This guide will demystify that language, so you can stop wondering and start using those colors to become a faster, more intuitive coder.

First Off, What Is Syntax Highlighting?

At its most basic, syntax highlighting is the feature in your Integrated Development Environment (IDE) or code editor (like VS Code, Sublime Text, or a JetBrains IDE) that displays text in different colors and fonts according to the category of terms. It’s not just for making your code look like a rainbow; it serves two critical purposes:

Readability: It helps you visually parse code much faster than you could with a wall of monochrome text. You can instantly distinguish between a variable, a string, a number, and a keyword.
Error Detection: If you have a typo in a keyword or a string that isn't closed, it will often show up in the “wrong” color, giving you an immediate visual cue that something is amiss.

This magic is powered by a parser that understands the grammar of your chosen programming language. It breaks your code down into a series of “tokens” (e.g., `keyword`, `function`, `variable`, `string`) and then your editor’s theme applies a specific color to each token type.

The Core Reason: It’s All About Context

So, why would the same function name appear in different colors? Because your editor is smart enough to know the difference between defining a function and using it. This is the most common reason for color variation.

Here are the primary contexts your editor is trying to show you:

Function Declaration/Definition: This is where you create the function, giving it a name and defining what it does. Editors often highlight this with a primary, attention-grabbing color (like a bright yellow or orange) because it represents a significant structural element in your code.
```
// The name 'createGreeting' here is the declaration
function createGreeting(name) {
  return `Hello, ${name}!`;
}
```
Function Call/Invocation: This is where you execute the function you’ve defined. The color here is often different (perhaps a light blue or cyan) to distinguish an action from a definition.
```
// The name 'createGreeting' here is the call/invocation
const message = createGreeting("Alice");
```
Built-in / Standard Library Functions: These are functions provided by the language itself or its core environment (e.g., console.log in JavaScript, print in Python, strlen in C). They often get a special color (like green or teal) to signal that they are part of the platform's standard API, not something you wrote.
Method Call: A method is simply a function that belongs to an object or a class. Your editor might give these their own color or a slight variation to show they are being called in the context of an object. Notice how myArray.push() might look different from a standalone function call.

Cracking the Code: Common Color Meanings for Functions

Important disclaimer: The exact colors depend entirely on your theme! What’s yellow in Monokai Pro might be purple in Dracula or orange in Solarized Dark. The table below represents common conventions, not universal rules. The key is the difference in colors, not the specific hues.

Example Color	What It Often Means	Common Scenarios
Bright Yellow / Orange	Function Declaration	`function myFunction() {}` or `const myFunction = () => {}`
Light Blue / Cyan	Function Call (User-Defined)	`const result = myFunction();`
Teal / Green	Built-in or API Call	`console.log('Hello');` or `document.getElementById('app');`
Slightly different Blue or White	Method Call (on an object)	`myArray.push(5);` or `user.getName();`

Let's See It in Action: A Practical Example

Let's look at a complete JavaScript snippet. Imagine you're viewing this in a typical modern editor. Pay attention to the comments, which explain the likely color-coding.

// A simple utility object
const StringUtils = {
  // METHOD DECLARATION: Might be colored like a function declaration (e.g., yellow)
  capitalize(str) {
    if (!str) return '';
    return str.charAt(0).toUpperCase() + str.slice(1);
  }
};

// FUNCTION DECLARATION: Often a primary color like yellow.
function logUserWelcome(user) {
  // METHOD CALL on an object: Often a distinct color like white or a different blue.
  const capitalizedName = StringUtils.capitalize(user.name);

  const message = `Welcome, ${capitalizedName}!`;

  // BUILT-IN/API CALL: Often a special color like teal or green.
  console.log(message);
}

const user = { id: 1, name: 'alex' };

// FUNCTION CALL: Often a secondary color like light blue.
logUserWelcome(user);

In this single block of code, the name capitalize appears in a different context (and likely color) than logUserWelcome, which itself appears in two different colors for its declaration and its call. And console.log stands apart from all of them. This is your editor giving you a rich, contextual map of your code's architecture.

Beyond the Defaults: Becoming a Theme Power-User

What if you don't like the colors? Or what if you want to make the distinction even clearer? You can! Most modern editors allow you to customize your syntax highlighting.

In an editor like VS Code, this is handled by a system of "scopes." Every token in your code is assigned a scope name, like entity.name.function for a function declaration or support.function for a built-in function. Your theme then maps these scopes to colors.

You can see these scopes for yourself! In VS Code, open your command palette (Ctrl+Shift+P or Cmd+Shift+P) and run the Developer: Inspect Editor Tokens and Scopes command. Click on any function name, and you'll see a detailed breakdown of its scope and what color rule is being applied.

Want to change the color of all function calls? You can add an override to your settings.json file:

"editor.tokenColorCustomizations": {
  "textMateRules": [
    {
      "scope": [
        "meta.function-call entity.name.function", // A common scope for function calls
        "support.function" // Targets built-in functions
      ],
      "settings": {
        "foreground": "#FFD700", // A nice gold color
        "fontStyle": "italic"
      }
    }
  ]
}

Diving into customization can be a rabbit hole, but it allows you to fine-tune your coding environment to be exactly as you like it.

Conclusion: Trust the Colors

The different colors for your functions aren't random noise; they're a signal. They’re your editor’s silent, helpful partner, constantly providing context about your code's structure and behavior.

Once you learn to read this visual language, you'll find you can navigate and understand codebases faster. You'll spot the difference between a definition and an invocation from across the room. So the next time you see your functions light up in different colors, don't worry. Instead, take a moment to appreciate the subtle, powerful information your editor is giving you. It's one of the best tools you have for writing clean, correct, and readable code.