mirror of
https://github.com/cesanta/mongoose.git
synced 2024-12-22 23:28:06 +08:00
60 lines
2.2 KiB
HTML
60 lines
2.2 KiB
HTML
|
<!DOCTYPE html>
|
||
|
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>example</title>
|
||
|
|
<meta charset="utf-8" />
|
||
|
|
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
|
||
|
|
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
|
||
|
|
<style>
|
||
|
|
#container { margin-right: auto; margin-left: auto; max-width: 480px; }
|
||
|
|
#info { background: #e0f0f0; border-radius: .5em; padding: 2em; margin-bottom: 1em; }
|
||
|
|
#result { margin-top: 1em; }
|
||
|
|
</style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div id="container">
|
||
|
|
<div id="info">
|
||
|
|
On devices with limited RAM, it is important to limit the response size
|
||
|
|
of API calls. This example demonstrates how to fetch a large
|
||
|
|
data in smaller chunks, and guarantee its integrity.
|
||
|
|
Data gets returned in a series of request/response transactions,
|
||
|
|
where each response is small enough to fit into available device RAM.
|
||
|
|
<br/><br/>
|
||
|
|
Data integrity is implemented by versioning.
|
||
|
|
The idea is that the first response includes the current "version" of the
|
||
|
|
data, and that version is passed to all subsequent requests.
|
||
|
|
If data version changes in the middle of the request series,
|
||
|
|
client fails with 'wrong version' error.
|
||
|
|
</div>
|
||
|
|
<button id="btn">fetch data</button>
|
||
|
|
<div id="result"></div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
<script>
|
||
|
|
const getchunk = (start, version) =>
|
||
|
|
fetch('/api/data', {method: 'POST', body:JSON.stringify({start, version})})
|
||
|
|
.then(r => r.json());
|
||
|
|
document.getElementById('btn').onclick = function() {
|
||
|
|
var data = [], version = 0;
|
||
|
|
const load = offset => getchunk(offset, version)
|
||
|
|
.then(r => {
|
||
|
|
// console.log(r);
|
||
|
|
if (r.error) {
|
||
|
|
document.getElementById('result').innerText = 'Error: ' + r.error;
|
||
|
|
} else {
|
||
|
|
version = r.version;
|
||
|
|
data = data.concat(r.data);
|
||
|
|
if (r.data.length == 0) {
|
||
|
|
document.getElementById('result').innerText = 'Version: ' +
|
||
|
|
version + ', data: \n' +
|
||
|
|
JSON.stringify(data, null, 2);
|
||
|
|
} else {
|
||
|
|
load(offset + r.data.length, version);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
});
|
||
|
|
load(0);
|
||
|
|
};
|
||
|
|
</script>
|
||
|
|
</html>
|