JavaScript类方法不起作用
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我有以下代码,这些代码是为移动应用程序开发的Titanium框架编写的.我遇到的问题是loadPage()方法未调用其他方法.我在这里想念什么？
Titanium.UI.currentWindow.barColor = Titanium.UI.currentWindow.barColor;
Titanium.UI.currentWindow.title = 'My Media';
function Media()
{
this.properties = {
currentPage : 1,
url : 'http://localhost/past?return=json&count=20&page=',
rowColor: '#fff',
rowSelectedColor: '#6BBBFA',
filter: 'filter'
};
this.table = false;
this.wrapper = false;
this.products = false;
/*
Allow the user to search through all of their media
*/
this.showSearch = function()
{
var search = Titanium.UI.createSearchBar({
barColor: Titanium.UI.currentWindow.barColor,
showCancel: false
});
search.addEventListener('change', function(e)
{
e.value; // search string as user types
});
search.addEventListener('return', function(e)
{
search.blur();
});
search.addEventListener('cancel', function(e)
{
search.blur();
});
return search;
};
/*
Create a row in the table. This will actually
append the row to a pre-existing table
*/
this.createRow = function(product)
{
var row = Ti.UI.createTableViewRow();
var image = Ti.UI.createImageView({
image: product.image,
top: 5,
left: 5,
width:100,
height:70,
canScale: true
});
var video = Ti.UI.createLabel({
color: '#000',
font: {
fontSize: 14,
fontWeight: 'bold',
fontFamily: 'Arial'
},
left: 110,
top: 2,
height: 20,
width: 170,
clickName: 'video',
text: product.name
});
var date = Ti.UI.createLabel({
color: '#999',
font: {
fontSize: 13,
fontWeight: 'normal',
fontFamily: 'Arial'
},
left: 110,
top: 22,
height: 20,
width: 100,
clickName: 'date',
text: product.date
});
row.height = 80;
row.className = 'mediaItem';
row.selectedBackgroundColor = this.properties.rowSelectedColor;
row.hasDetail = true;
row.filter = video.text;
row.add(image);
row.add(video);
row.add(date);
// Add the row to the table
this.addRowToTable(row);
};
/*
Add the products to the table view
*/
this.addRows = function()
{
var item;
for(item in this.products)
{
if(item)
{
this.createRow(this.products[item]);
}
}
this.showMoreButton();
};
/*
If we do not already have a table, let's go ahead and build one now
*/
this.buildTable = function()
{
if(!this.table)
{
// Build out the table
this.table = Titanium.UI.createTableView({
search: this.showSearch(),
filterAttribute: this.properties.filter,
backgroundColor: '#ffffff'
});
this.wrapperView = Titanium.UI.createView({
backgroundColor: 'transparent'
});
this.wrapperView.add(this.table);
Titanium.UI.currentWindow.add(this.wrapperView);
}
};
/*
Append a row to the table (if the table exists)
*/
this.addRowToTable = function(row)
{
if(this.table)
{
this.table.appendRow(row);
}
};
/*
Allow the user to choose to show more videos
*/
this.showMoreButton = function()
{
var row = Ti.UI.createTableViewRow();
row.backgroundColor = '#6BBBFA';
row.selectedBackgroundColor = '#666';
// add custom property to identify this row
row.isUpdateRow = true;
var rowText = Ti.UI.createLabel({
color: '#fff',
font: {
fontSize:16,
fontWeight:'bold'
},
text: 'Show More Videos',
width: 'auto',
height: 'auto'
});
row.className = 'updated_row';
row.add(rowText);
row.addEventListener('click', function(e){
this.loadPage();
});
// Add the row to the table
this.addRowToTable(row);
};
/*
We don't want to load the same page
multiple times, so increment the page each time
*/
this.incrementPage = function()
{
this.properties.currentPage = this.properties.currentPage + 1;
};
/*
Let's go ahead and load a URL and parse it as JSON
This method will automatically paginate
*/
this.loadPage = function()
{
xhr = Titanium.Network.createHTTPClient();
xhr.open('GET', this.properties.url + this.properties.currentPage);
xhr.onload = function()
{
// Set the response
var response = JSON.parse(xhr.responseText);
this.products = response.products;
// Build the table. This method will only build it if it doesn't yet exist
this.buildTable();
// Add rows to the table
this.addRows();
// Go ahead and increment the page that we are on
this.incrementPage();
};
xhr.onerror = function(e)
{
// If there has been an error, let the user know about it
var a = Titanium.UI.createAlertDialog({
title:'Error',
message: 'There was an error with the request. Please try again later'
});
a.show();
};
xhr.send();
};
};
var media = new Media();
media.loadPage();
解决方法:
你有范围问题.当你到这一点
xhr.onload = function()
{
// Set the response
var response = JSON.parse(xhr.responseText);
this.products = response.products;
// Build the table. This method will only build it if it doesn't yet exist
this.buildTable();
// Add rows to the table
this.addRows();
// Go ahead and increment the page that we are on
this.incrementPage();
};
引用xhr而不是Media对象的名称.通常可以通过在Media构造函数的顶部创建一个指向自身的新变量来解决此问题,例如
function Media()
{
var self = this;
然后,您将使用自身名称从xhr.onload中引用Media对象.
xhr.onload = function()
{
// Set the response
var response = JSON.parse(xhr.responseText);
self.products = response.products;
// Build the table. This method will only build it if it doesn't yet exist
self.buildTable();
...
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