File System Access 追加写入与区间覆盖实践

概述追加与区间覆盖可提高更新效率。本文提供最小用法。追加与覆盖async function appendText() { const handle = await window.showSaveFilePicker({ suggestedName: 'log.txt' }); const ws = await handle.createWritable({ keepExistingData: true }); const file = await handle.getFile(); await ws.seek(file.size); await ws.write(new Blob(['\nappend line'], { type: 'text/plain' })); await ws.close(); } async function coverRange(pos, bytes) { const handle = await window.showSaveFilePicker({ suggestedName: 'data.bin' }); const ws = await handle.createWritable({ keepExistingData: true }); await ws.write({ type: 'write', position: pos, data: bytes }); await ws.close(); }