將額外參數傳遞給WebSQL回調函數？

Question

我打電話的功能db.transaction與下面的代碼：

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

功能createSheetDB是一個回調函數，其隱含db.transaction稱爲（），這也傳遞給它的參數TX。我已經實現的功能createSheetDB（TX）是這樣的：

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)} 
);} 

現在的問題是SHEETNAME和降序的值僅在調用函數中是可用的。我如何將它們傳遞到函數createSheetDB（tx）？

Answer 1

您可以使用一種技術來創建一個新的回調函數，該回調函數將關閉您想要的變量。

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

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

(function() { 

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

    doStuff(anotherCallback); 

}());​ 

Answer 2

回調創建一個功能

function createSheetDB(sheetName, desc) { 
    return function(tx){ 
     var nextId = 1; 
     alert("INSERT INTO SHEET(id, name, desc) VALUES("+nextId+",'"+sheetName+"','"+desc+"')"); 
     /* delete above two lines and uncomment for your code 
     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)} 
     ); 
     */ 
    } 
} 

// dummy code to show as example 
db = {transaction: function(fn,lose,win){return fn(),win();}}; 

function testIt(){ 
    var sheetName = 'hello', 
     desc = 'world'; 
    db.transaction(createSheetDB(sheetName, desc), function(){alert("Sheet creation error!")}, function(){alert("Sheet created!")}); 
    // note how createSheetDB is now called with the vars you want 
}