html-tools/html-formatter.html at main · levups/html-tools · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>HTML Formatter</title>
    <link rel="stylesheet" href="common.css">
    <style>
        body { display: flex; flex-direction: column; }
        .options { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
    </style>
</head>
<body>

    <a href="index.html" class="back-link">
        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
            <path d="M19 12H5M12 19l-7-7 7-7"/>
        </svg>
        All Tools
    </a>

    <header>
        <h1>HTML Formatter</h1>
        <p class="subtitle">Pretty print or minify HTML</p>
    </header>

    <div class="controls">
        <button id="formatBtn">Format</button>
        <button id="minifyBtn">Minify</button>
        <button id="clearBtn" class="secondary">Clear</button>
        <div class="options">
            <div class="option-group">
                <label for="indentSelect">Indent:</label>
                <select id="indentSelect">
                    <option value="2">2 spaces</option>
                    <option value="4">4 spaces</option>
                    <option value="tab">Tab</option>
                </select>
            </div>
        </div>
    </div>

    <div class="container">
        <div class="pane">
            <div class="pane-header">
                <span class="label">
                    <svg class="icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
                        <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"></path>
                        <polyline points="14 2 14 8 20 8"></polyline>
                    </svg>
                    Input
                    <span id="statusIndicator" class="status-indicator"></span>
                </span>
            </div>
            <textarea id="inputArea" placeholder='Paste your HTML here...

Example:
<div><p>Hello</p><span>World</span></div>' spellcheck="false"></textarea>
            <div id="errorMessage" class="error-message"></div>
        </div>

        <div class="pane">
            <div class="pane-header">
                <span class="label">
                    <svg class="icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
                        <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"></path>
                        <polyline points="14 2 14 8 20 8"></polyline>
                        <line x1="16" y1="13" x2="8" y2="13"></line>
                        <line x1="16" y1="17" x2="8" y2="17"></line>
                    </svg>
                    Output
                </span>
                <button id="copyBtn" class="copy-btn">Copy</button>
            </div>
            <textarea id="outputArea" readonly placeholder="Formatted HTML will appear here..." spellcheck="false"></textarea>
        </div>
    </div>

    <script>
        const inputArea = document.getElementById('inputArea');
        const outputArea = document.getElementById('outputArea');
        const formatBtn = document.getElementById('formatBtn');
        const minifyBtn = document.getElementById('minifyBtn');
        const clearBtn = document.getElementById('clearBtn');
        const copyBtn = document.getElementById('copyBtn');
        const indentSelect = document.getElementById('indentSelect');
        const errorMessage = document.getElementById('errorMessage');
        const statusIndicator = document.getElementById('statusIndicator');

        // Void elements that don't have closing tags
        const voidElements = new Set([
            'area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input',
            'link', 'meta', 'param', 'source', 'track', 'wbr'
        ]);

        // Elements that should preserve whitespace
        const preserveWhitespaceElements = new Set(['pre', 'code', 'textarea', 'script', 'style']);

        // Inline elements that shouldn't add newlines
        const inlineElements = new Set([
            'a', 'abbr', 'acronym', 'b', 'bdo', 'big', 'br', 'button', 'cite',
            'code', 'dfn', 'em', 'i', 'img', 'input', 'kbd', 'label', 'map',
            'object', 'output', 'q', 'samp', 'select', 'small', 'span', 'strong',
            'sub', 'sup', 'textarea', 'time', 'tt', 'var'
        ]);

        function getIndent(indentValue) {
            return indentValue === 'tab' ? '\t' : ' '.repeat(parseInt(indentValue, 10));
        }

        function formatNode(node, indent, level, preserveWS) {
            const indentStr = indent.repeat(level);
            let result = '';

            if (node.nodeType === Node.TEXT_NODE) {
                const text = node.textContent;
                if (preserveWS) {
                    return text;
                }
                const trimmed = text.trim();
                if (!trimmed) return '';
                return trimmed;
            }

            if (node.nodeType === Node.COMMENT_NODE) {
                return `${indentStr}<!--${node.textContent}-->`;
            }

            if (node.nodeType === Node.DOCUMENT_TYPE_NODE) {
                return `<!DOCTYPE ${node.name}>`;
            }

            if (node.nodeType !== Node.ELEMENT_NODE) {
                return '';
            }

            const tagName = node.tagName.toLowerCase();
            const isVoid = voidElements.has(tagName);
            const shouldPreserveWS = preserveWhitespaceElements.has(tagName);
            const isInline = inlineElements.has(tagName);

            // Build opening tag
            let openTag = `<${tagName}`;
            for (const attr of node.attributes) {
                openTag += ` ${attr.name}="${attr.value.replace(/"/g, '&quot;')}"`;
            }

            if (isVoid) {
                return `${indentStr}${openTag}>`;
            }

            openTag += '>';

            // Handle content
            const children = Array.from(node.childNodes);

            if (children.length === 0) {
                return `${indentStr}${openTag}</${tagName}>`;
            }

            if (shouldPreserveWS) {
                // Preserve whitespace for pre, code, etc.
                let content = '';
                for (const child of children) {
                    if (child.nodeType === Node.TEXT_NODE) {
                        content += child.textContent;
                    } else if (child.nodeType === Node.ELEMENT_NODE) {
                        content += formatNode(child, indent, 0, true);
                    }
                }
                return `${indentStr}${openTag}${content}</${tagName}>`;
            }

            // Check if content is simple (single text node or only inline elements with text)
            const hasBlockChildren = children.some(child =>
                child.nodeType === Node.ELEMENT_NODE && !inlineElements.has(child.tagName.toLowerCase())
            );

            const onlyTextAndInline = children.every(child =>
                child.nodeType === Node.TEXT_NODE ||
                (child.nodeType === Node.ELEMENT_NODE && inlineElements.has(child.tagName.toLowerCase()))
            );

            if (onlyTextAndInline && !hasBlockChildren) {
                // Keep inline content on same line
                let content = '';
                for (const child of children) {
                    content += formatNode(child, indent, 0, false);
                }
                return `${indentStr}${openTag}${content}</${tagName}>`;
            }

            // Multi-line formatting for block content
            result = `${indentStr}${openTag}\n`;
            for (const child of children) {
                const childResult = formatNode(child, indent, level + 1, false);
                if (childResult) {
                    result += childResult + '\n';
                }
            }
            result += `${indentStr}</${tagName}>`;

            return result;
        }

        function formatHTML(html, indent) {
            // Parse as HTML fragment
            const parser = new DOMParser();
            const doc = parser.parseFromString(html, 'text/html');

            // Check for parsing errors in body
            const errorNode = doc.querySelector('parsererror');
            if (errorNode) {
                throw new Error('Invalid HTML: ' + errorNode.textContent);
            }

            // Determine what to format
            let result = '';

            // Check if input has doctype or html/head/body
            const hasFullDoc = html.trim().toLowerCase().startsWith('<!doctype') ||
                              html.trim().toLowerCase().startsWith('<html');

            if (hasFullDoc) {
                // Format full document
                if (doc.doctype) {
                    result += formatNode(doc.doctype, indent, 0, false) + '\n';
                }
                result += formatNode(doc.documentElement, indent, 0, false);
            } else {
                // Format just the body content (fragment mode)
                const body = doc.body;
                const lines = [];
                for (const child of body.childNodes) {
                    const formatted = formatNode(child, indent, 0, false);
                    if (formatted) {
                        lines.push(formatted);
                    }
                }
                result = lines.join('\n');
            }

            return result;
        }

        function minifyHTML(html) {
            // Parse as HTML fragment
            const parser = new DOMParser();
            const doc = parser.parseFromString(html, 'text/html');

            function minifyNode(node) {
                if (node.nodeType === Node.TEXT_NODE) {
                    const tagName = node.parentElement?.tagName.toLowerCase();
                    if (preserveWhitespaceElements.has(tagName)) {
                        return node.textContent;
                    }
                    return node.textContent.replace(/\s+/g, ' ').trim();
                }

                if (node.nodeType === Node.COMMENT_NODE) {
                    return `<!--${node.textContent}-->`;
                }

                if (node.nodeType === Node.DOCUMENT_TYPE_NODE) {
                    return `<!DOCTYPE ${node.name}>`;
                }

                if (node.nodeType !== Node.ELEMENT_NODE) {
                    return '';
                }

                const tagName = node.tagName.toLowerCase();
                const isVoid = voidElements.has(tagName);
                const shouldPreserveWS = preserveWhitespaceElements.has(tagName);

                let openTag = `<${tagName}`;
                for (const attr of node.attributes) {
                    openTag += ` ${attr.name}="${attr.value.replace(/"/g, '&quot;')}"`;
                }
                openTag += '>';

                if (isVoid) {
                    return openTag;
                }

                let content = '';
                for (const child of node.childNodes) {
                    const minified = minifyNode(child);
                    if (shouldPreserveWS) {
                        content += minified;
                    } else if (minified) {
                        content += minified;
                    }
                }

                return `${openTag}${content}</${tagName}>`;
            }

            const hasFullDoc = html.trim().toLowerCase().startsWith('<!doctype') ||
                              html.trim().toLowerCase().startsWith('<html');

            if (hasFullDoc) {
                let result = '';
                if (doc.doctype) {
                    result += minifyNode(doc.doctype);
                }
                result += minifyNode(doc.documentElement);
                return result;
            } else {
                let result = '';
                for (const child of doc.body.childNodes) {
                    result += minifyNode(child);
                }
                return result;
            }
        }

        function format(minify = false) {
            const input = inputArea.value.trim();

            errorMessage.style.display = 'none';
            statusIndicator.className = 'status-indicator';

            if (!input) {
                outputArea.value = '';
                return;
            }

            try {
                if (minify) {
                    outputArea.value = minifyHTML(input);
                } else {
                    const indent = getIndent(indentSelect.value);
                    outputArea.value = formatHTML(input, indent);
                }
                statusIndicator.className = 'status-indicator valid';
            } catch (e) {
                errorMessage.style.display = 'block';
                errorMessage.textContent = e.message;
                outputArea.value = '';
                statusIndicator.className = 'status-indicator invalid';
            }
        }

        formatBtn.addEventListener('click', () => format(false));
        minifyBtn.addEventListener('click', () => format(true));

        // Auto-format on input
        inputArea.addEventListener('input', () => format(false));

        clearBtn.addEventListener('click', () => {
            inputArea.value = '';
            outputArea.value = '';
            errorMessage.style.display = 'none';
            statusIndicator.className = 'status-indicator';
            inputArea.focus();
        });

        copyBtn.addEventListener('click', () => {
            if (!outputArea.value) return;
            navigator.clipboard.writeText(outputArea.value).then(() => {
                const originalText = copyBtn.textContent;
                copyBtn.textContent = 'Copied!';
                copyBtn.classList.add('copied');
                setTimeout(() => {
                    copyBtn.textContent = originalText;
                    copyBtn.classList.remove('copied');
                }, 2000);
            });
        });

        // Re-format when options change
        indentSelect.addEventListener('change', () => format(false));
    </script>
</body>
</html>