我仍然是初学者，所以我希望这是有道理的。
我正在尝试将带有 IndexedDB 事务/游标的函数的返回变量导出到带有 get 事务的另一个模块，但是该请求始终未定义。是否可以将 IndexedDB 函数的值传递给同一域内的其他模块？
db.js - 我正在导出的函数
...
function getAllData() {
// can use getAll() however not as efficient.
// let data = [];
let data = [];
let store = db.transaction("forms").objectStore("forms");
store.openCursor().onsuccess = (event) => {
let cursor = event.target.result;
if (cursor) {
console.log("FORM name is " + cursor.value.name + " and form counter is " + cursor.key);
// data.push(cursor.value.name);
data.push(cursor.value);
cursor.continue();
} else {
console.log("All entries retrieved");
console.log("the data form.name is " + data);
console.log("the data is " + data.length);
return data.length;
}
}
store.openCursor().onerror = event => {
console.log("Error in getting all data " + event.target.errorCode);
}
};
export { getAllData } ;
js
import { getAlldData } from './db.js'
(() => {
function getIndex() {
let formData = getAllData();
console.log("the counter is " + formData); // shows formData as undefined
}
}
)();
是否可以在a.js formData 中获取db.js getAllData()的返回值？他们在 db.js 中正确地 console.log
我看到你让它与回调一起工作。这是使用承诺的示例。
export function getAllData() {
return new Promise((resolve, reject) => {
let data = [];
let store = db.transaction("forms").objectStore("forms");
const request = store.openCursor();
request.onsuccess = (event) => {
let cursor = event.target.result;
if (cursor) {
data.push(cursor.value);
cursor.continue();
} else {
resolve(data);
}
};
request.onerror = event => {
reject(new Error('Error getting all data'));
};
});
};
// and then to use it in another module you do this:
import { getAllData } from 'file';
getAllData().then(data => {
console.log('loaded %d rows', data.length);
for (const row of data) {
console.log('row of data:', JSON.stringify(row));
}
}).catch(error => {
console.log('got an error :( - ', error.message);
});
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我来说两句