将额外的参数传递给 WebSQL 回调函数? [英] Pass extra parameters to WebSQL callback function?

问题描述

我正在使用以下代码调用函数 db.transaction:

I am calling a function db.transaction with following code:

    db.transaction(createSheetDB, function(){alert("Sheet creation error!")}, function(){alert("Sheet created!")});

函数 createSheetDB 是一个回调函数，它被 db.transaction() 隐式调用，它也传递一个参数 tx.我已经实现了这样的函数 createSheetDB(tx):

The function createSheetDB is a callback function which is implicitly called by db.transaction() which also passes it a parameter tx. I have implemented function createSheetDB(tx) like this:

function createSheetDB(tx) {
var nextId = getNextId();
tx.executeSql("INSERT INTO SHEET(id, name, desc) VALUES("+nextId+",'"+sheetName+"','"+desc+"')", [], 
        function(){alert("Sheet row inserted!")}, 
        function(tx, err){alert("Sheet row insertion Error: "+err.message+" "+err.code)}
);}

现在的问题是 sheetName 和 desc 的值仅在调用函数中可用.我如何将它们传递给函数 createSheetDB(tx)?

Now the problem is the values of sheetName and desc are available only in the calling function. How do I pass them onto function createSheetDB(tx)?

推荐答案

您可以使用一种技术来创建一个新回调，该回调将关闭您想要的变量.

You can use a technique whereby you create a new callback that will close over the variables you want.

function doStuff(callback) {
    var val = 43;
    callback(val);
}

function myCallback(val, anotherVal) {
    alert("val: " + val + "
anotherVal: " + anotherVal);
}

(function() {

    var anotherVal = "Whoa!",
        anotherCallback = function(val) {
            return myCallback(val, anotherVal);
        };

    doStuff(anotherCallback);

}());​

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