Introduction to CodeMirror
CodeMirror is a versatile and powerful code editor implemented in JavaScript for the browser. It can be customized to fit your exact needs and has a vast array of APIs that help streamline web development. In this blog post, we will delve into various useful CodeMirror APIs, complete with code snippets, and provide an application example utilizing these APIs.
Setting Up CodeMirror
Before diving into the APIs, let’s set up CodeMirror in your project:
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.2/codemirror.min.css"> <script src="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.2/codemirror.min.js"></script>
API Examples
1. Basic Initialization
var editor = CodeMirror.fromTextArea(document.getElementById('code'), {
mode: "javascript",
lineNumbers: true
});
2. Changing Themes
editor.setOption("theme", "monokai");
3. Adding Custom Key Bindings
editor.setOption("extraKeys", {
"Ctrl-Space": "autocomplete",
"Ctrl-S": function(instance) { saveDocument(instance); }
});
4. Handling Events
editor.on("change", function(instance, changes) {
console.log("Document changed: ", changes);
});
5. Working with Documents
var doc = editor.getDoc();
var cursor = doc.getCursor();
console.log("Cursor position: ", cursor);
6. Code Folding
CodeMirror.defineExtension("autoFold", function() {
var range = this.findMatchingBracket(this.getCursor());
if (range) this.foldCode(range.to, null, "fold");
});
7. Undo and Redo
editor.undo(); editor.redo();
8. Searching and Replacing
var cursor = editor.getSearchCursor("function");
while (cursor.findNext()) {
cursor.replace("fn");
}
9. Setting Gutter Markers
editor.setGutterMarker(5, "breakpoints", makeMarker());
10. Adding Widgets
editor.addWidget({line: 10, ch: 0}, document.createElement("div"), true);
Example Application
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.2/codemirror.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.2/codemirror.min.js"></script>
</head>
<body>
<textarea id="code">console.log("Hello, world!");</textarea>
<script>
var editor = CodeMirror.fromTextArea(document.getElementById('code'), {
mode: "javascript",
lineNumbers: true,
theme: "monokai",
extraKeys: {
"Ctrl-Space": "autocomplete",
"Ctrl-S": function(instance) { alert("Document Saved!"); }
}
});
editor.on("change", function(instance, changes) {
console.log("Document changed: ", changes);
});
</script>
</body>
</html>
By leveraging the extensive CodeMirror APIs, you can create a highly functional and customizable code editor tailored to your specific needs. Whether you want to set breakpoints, fold code, or handle custom events, CodeMirror provides you with all the tools necessary to build an exceptional coding environment within your web application.
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