Paances Liao
新穎時尚
使用 File Handling API
首先，請在網頁應用程式資訊清單中宣告 file_handlers 屬性。File Handling API 要求您必須指定 action 屬性 (處理網址) 和 accept 屬性，這是以 MIME 類型表示的物件和陣列，其中具有特別對應副檔名的鍵和陣列。
{
"file_handlers": [
{
"action": "./",
"accept": {
"image/*": [".jpg", ".jpeg", ".png", ".webp", ".svg"]
}
}
]
}
接下來，您需要使用 File Handling API 透過 launchQueue 強制處理已開啟的檔案。
if ('launchQueue' in window && 'files' in LaunchParams.prototype) {
launchQueue.setConsumer((launchParams) => {
if (!launchParams.files.length) {
return;
}
for (const fileHandle of launchParams.files) {
// Handle the file.
}
});
}
瀏覽器支援
- 102
- 102
- x
- x
經典風格
使用傳統版 DataTransferItem.getAsFile() 方法
如果不支援 File Handling API，您仍可從檔案探索工具將檔案拖曳到應用程式中。DataTransferItem.getAsFile() 方法會傳回拖曳資料項目的 File 物件。如果項目不是檔案，此方法會傳回 null。雖然您可以讀取檔案，但無法寫回檔案。這種方法的缺點是不支援目錄。
漸進增強
下方的程式碼片段會在檔案處理時使用 File Handling API，並額外註冊拖曳處理常式，以便處理拖曳的檔案。
宣告可在網頁應用程式資訊清單中處理的檔案類型。瀏覽器如果不支援 File Handling API，則會忽略此 API。
{
"file_handlers": [
{
"action": "./",
"accept": {
"image/*": [".jpg", ".jpeg", ".png", ".webp", ".svg"]
}
}
]
}
// File Handling API
const handleLaunchFiles = () => {
window.launchQueue.setConsumer((launchParams) => {
if (!launchParams.files.length) {
return;
}
launchParams.files.forEach(async (handle) => {
const file = await handle.getFile();
console.log(`File: ${file.name}`);
// Do something with the file.
});
});
};
if ('launchQueue' in window && 'files' in LaunchParams.prototype) {
handleLaunchFiles();
}
// This is the drag and drop zone.
const elem = document.querySelector('main');
// Prevent navigation.
elem.addEventListener('dragover', (e) => {
e.preventDefault();
});
// Visually highlight the drop zone.
elem.addEventListener('dragenter', (e) => {
elem.style.outline = 'solid red 1px';
});
// Visually unhighlight the drop zone.
elem.addEventListener('dragleave', (e) => {
elem.style.outline = '';
});
// This is where the drop is handled.
elem.addEventListener('drop', async (e) => {
// Prevent navigation.
e.preventDefault();
// Unhighlight the drop zone.
elem.style.outline = '';
// Prepare an array of promises…
const fileHandlesPromises = [...e.dataTransfer.items]
// …by including only files (where file misleadingly means actual file _or_
// directory)…
.filter((item) => item.kind === 'file')
// …and, depending on previous feature detection…
.map((item) => item.getAsFile());
// Loop over the array of promises.
for await (const handle of fileHandlesPromises) {
// This is where we can actually exclusively act on the files.
if (handle.isFile) {
console.log(`File: ${handle.name}`);
// Do something with the file.
}
}
});
其他資訊
示範
HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link rel="manifest" href="manifest.json" />
<title>How to handle files opened from the file explorer</title>
<link rel="stylesheet" href="style.css" />
<!-- TODO: Devsite - Removed inline handlers -->
<!-- <script>
if ('serviceWorker' in navigator) {
window.addEventListener('load', async () => {
const registration = await navigator.serviceWorker.register(
'sw.js',
);
console.log(
'Service worker registered for scope',
registration.scope,
);
});
}
</script>
<script src="script.js" type="module"></script> -->
</head>
<body>
<h1>How to handle files opened from the file explorer</h1>
<p>Install the app. After the installation, try opening an image file from the file explorer with the app.
</body>
</html>CSS
html {
box-sizing: border-box;
font-family: system-ui, sans-serif;
color-scheme: dark light;
}
*, *:before, *:after {
box-sizing: inherit;
}
body {
margin: 1rem;
}
img {
height: auto;
max-width: 100%;
display: block;
}
JS
if ('launchQueue' in window && 'files' in LaunchParams.prototype) {
launchQueue.setConsumer((launchParams) => {
if (!launchParams.files.length) {
return;
}
for (const fileHandle of launchParams.files) {
document.body.innerHTML += `${fileHandle.name}
`;
}
});
}