嗨我对Print Plugin或Phonegap插件的某些部分感到很困惑。看到我能够实现代码甚至创建我自己的插件,但我没有从objective-c(xcode)返回到javascript的值,所以可以说它很容易理解。
关于此代码:
https://github.com/phonegap/phonegap-plugins/blob/master/iPhone/PrintPlugin/PrintPlugin.js
在这段代码上:
PrintPlugin.prototype.callbackMap = {};
PrintPlugin.prototype.callbackIdx = 0;
PrintPlugin.prototype.print = function(printHTML, success, fail, options) {
if (typeof printHTML != 'string'){
console.log("Print function requires an HTML string. Not an object");
return;
}
//var printHTML = "";
var dialogLeftPos = 0;
var dialogTopPos = 0;
if (options){
if (options.dialogOffset){
if (options.dialogOffset.left){
dialogLeftPos = options.dialogOffset.left;
if (isNaN(dialogLeftPos)){
dialogLeftPos = 0;
}
}
if (options.dialogOffset.top){
dialogTopPos = options.dialogOffset.top;
if (isNaN(dialogTopPos)){
dialogTopPos = 0;
}
}
}
}
var key = 'print' + this.callbackIdx++;
window.plugins.printPlugin.callbackMap[key] = {
success: function(result) {
delete window.plugins.printPlugin.callbackMap[key];
success(result);
},
fail: function(result) {
delete window.plugins.printPlugin.callbackMap[key];
fail(result);
},
};
var callbackPrefix = 'window.plugins.printPlugin.callbackMap.' + key;
return PhoneGap.exec("PrintPlugin.print", printHTML, callbackPrefix + '.success', callbackPrefix + '.fail', dialogLeftPos, dialogTopPos);
};
特别是这行代码:
PrintPlugin.prototype.callbackMap = {};
PrintPlugin.prototype.callbackIdx = 0;
我很困惑这两行代码的作用以及当你想要将值从xcode返回到javascript时,为什么它在某种程度上很重要:注意:由我说当你想要将值从xcode返回到javascript 时,为什么合并或遵循它是有点重要的我根据我到目前为止所理解的说法这是
有人可以解释两行代码如何工作以及它们的用途是什么?谢谢。