Introduction to CodeMirror
CodeMirror is a versatile text editor implemented in JavaScript for the browser. It is specialized for editing code and comes with a broad range of features and functionalities. Whether you are building an online code editor, integrating a markdown editor, or simply creating a form with syntax highlighting, CodeMirror is a robust choice. In this article, we will explore a wide array of CodeMirror APIs with practical code snippets and a comprehensive app example.
How to Get Started with CodeMirror
To begin using CodeMirror, you can include it in your project using a CDN:
<link rel="stylesheet" href="https://codemirror.net/lib/codemirror.css">
<script src="https://codemirror.net/lib/codemirror.js"></script>
Creating an Editor
The core of CodeMirror is the creation of an editor. Here’s how you can create a simple editor:
var myCodeMirror = CodeMirror(document.body, {
value: "// Your code here\n",
mode: "javascript"
});
Basic Configuration
Customizing the editor with various options:
var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
lineNumbers: true,
mode: "htmlmixed",
theme: "monokai",
readOnly: false
});
API Examples
Setting and Getting Value
Set and get the value of the editor:
editor.setValue("new value of the editor");
var content = editor.getValue();
console.log(content);
Event Handling
You can handle various events like change, focus, and blur:
editor.on("change", function(instance, changeObj) {
console.log("Editor content changed");
});
Adding and Removing Lines
Adding and removing lines at specific positions:
editor.replaceRange("New line\n", { line: 5, ch: 0 });
editor.removeLine(5);
Foldable Code
Folding and unfolding code blocks:
editor.foldCode(CodeMirror.Pos(10, 0));
Gutters and Highlighting
Adding gutters for line numbers or markers:
editor.setGutterMarker(3, "breakpoints", document.createElement("div"));
Comprehensive Example
Below is a comprehensive example integrating several CodeMirror features into a small app:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://codemirror.net/lib/codemirror.css">
<script src="https://codemirror.net/lib/codemirror.js"></script>
<script src="https://codemirror.net/mode/javascript/javascript.js"></script>
</head>
<body>
<textarea id="code"></textarea>
<script>
var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
lineNumbers: true,
mode: "javascript",
theme: "monokai"
});
editor.on("change", function(instance, changeObj) {
console.log("Content changed: ", instance.getValue());
});
editor.setValue("// Start coding here!\nfunction greet() {\n alert('Hello, world!');\n}");
</script>
</body>
</html>
The above code sets up a CodeMirror instance with JavaScript mode, line numbers, and a monokai theme. It includes an event listener that logs changes to the console and initializes the editor with some content. Feel free to extend this example and adapt it to your needs.
CodeMirror presents a blend of simplicity and flexibility, making it a go-to solution for developers looking to add code editing capabilities to their web applications. With dozens of configuration options and a powerful API, the possibilities are vast.
Enjoy coding with CodeMirror!
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