如何在事务回调函数中传递参数 [英] how can I pass argument in transaction callback function

问题描述

从像这样的教程代码

function queryDB(tx) {
    tx.executeSql('SELECT * FROM DEMO', [], querySuccess, errorCB);
}

function querySuccess(tx, results) {

}

function errorCB(err) {
    alert("Error processing SQL: "+err.code);
}

var db = window.openDatabase("Database", "1.0", "PhoneGap Demo", 200000);
db.transaction(queryDB, errorCB); 

我想将一个变量作为参数传递给queryDB函数，所以我的代码想到应该看起来像

in db.transaction i want to pass a variable as argument to queryDB function, so the code which i think of should looks like

db.transaction(queryDB(id), errorCB);

我如何实际实现这个？或者它只是像这样工作，我的id将被传递并进入tx？

How I can actually implement this ? Or its simply gonna work like this and my id will be passed and get in tx ?

推荐答案

再次将它包裹在一个函数中

Wrap it in a function again

var id = 'THEID';
db.transaction(function(){
  queryDB(id)
}, errorCB);

注意 - 假设您正在制作API。某些API /框架会自动插入所需的信息。例如

Note - This is assuming that you're making the API. Some APIs / frameworks insert the required information automatically. For example

//the db.transaction method
function transaction(param, callback) {
   //do code stuff
   callback(someInternalId); //callback is the function you pass as the first parameter
}

所以，如果你想要在回调中传递您自己的数据，将其包装在函数中。否则，您使用的代码可能会自动为您执行此操作。

So, if you want to pass your own data in the callback, wrap it in a function. Otherwise, the code you are using may be doing this for you automatically.

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