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Merged
jackasser merged 1 commit into from
Jun 15, 2025
Merged

Add basic Mermaid flow editor #2

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4 changes: 4 additions & 0 deletions README.md
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Expand Up @@ -233,6 +233,10 @@ Check out these resources to learn more or get involved:
Add a link to get support, GitHub status page, code of conduct, license link.
-->

## Flow Editor

This repository includes a simple HTML based flow editor using [Mermaid](https://mermaid-js.github.io/). Open `flow-editor.html` in your browser to build diagrams. Use the GUI forms to add nodes or edges and edit the Mermaid code directly. Click **Save** to store to localStorage and **Load** to restore.

---

Get help: [Post in our discussion board](https://github.com/skills/.github/discussions) • [Review the GitHub status page](https://www.githubstatus.com/)
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102 changes: 102 additions & 0 deletions flow-editor.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Flow Editor</title>
<script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
<style>
body { font-family: Arial, sans-serif; margin: 20px; }
#diagram { border: 1px solid #ccc; padding: 10px; }
textarea { width: 100%; height: 200px; }
.controls { margin-top: 10px; }
.controls input { margin-right: 5px; }
</style>
</head>
<body>
<h1>Flow Editor</h1>
<textarea id="mermaidInput"></textarea>
<div class="controls">
<button id="updateBtn">Update</button>
<button id="saveBtn">Save</button>
<button id="loadBtn">Load</button>
</div>
<div class="controls">
<input type="text" id="nodeId" placeholder="Node ID">
<input type="text" id="nodeLabel" placeholder="Node label">
<button id="addNodeBtn">Add Node</button>
</div>
<div class="controls">
<input type="text" id="fromNode" placeholder="From">
<input type="text" id="toNode" placeholder="To">
<input type="text" id="edgeLabel" placeholder="Edge label">
<button id="addEdgeBtn">Add Edge</button>
</div>
<div id="diagram"></div>
<script>
mermaid.initialize({ startOnLoad: false });
const input = document.getElementById('mermaidInput');
const diagram = document.getElementById('diagram');

function render() {
const code = input.value;
mermaid.render('mermaidDiagram', code, svgCode => {
diagram.innerHTML = svgCode;
});
}

document.getElementById('updateBtn').addEventListener('click', render);
document.getElementById('saveBtn').addEventListener('click', () => {
localStorage.setItem('mermaidFlow', input.value);
});
document.getElementById('loadBtn').addEventListener('click', () => {
input.value = localStorage.getItem('mermaidFlow') || '';
render();
});

document.getElementById('addNodeBtn').addEventListener('click', () => {
const id = document.getElementById('nodeId').value.trim();
const label = document.getElementById('nodeLabel').value.trim();
if (!id) return;
const lines = input.value.trim().split('\n');
if (!lines[0]) {
lines[0] = 'graph LR';
}
lines.push(`${id}[${label || id}]`);
input.value = lines.join('\n');
document.getElementById('nodeId').value = '';
document.getElementById('nodeLabel').value = '';
render();
});

document.getElementById('addEdgeBtn').addEventListener('click', () => {
const from = document.getElementById('fromNode').value.trim();
const to = document.getElementById('toNode').value.trim();
const label = document.getElementById('edgeLabel').value.trim();
if (!from || !to) return;
const lines = input.value.trim().split('\n');
if (!lines[0]) {
lines[0] = 'graph LR';
}
if (label) {
lines.push(`${from} -->|${label}| ${to}`);
} else {
lines.push(`${from} --> ${to}`);
}
input.value = lines.join('\n');
document.getElementById('fromNode').value = '';
document.getElementById('toNode').value = '';
document.getElementById('edgeLabel').value = '';
render();
});

// load initial
const stored = localStorage.getItem('mermaidFlow');
if (stored) {
input.value = stored;
} else {
input.value = `graph LR\nA[Start] --> B[End]`;
}
render();
</script>
</body>
</html>