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SensorUtil 传感器工具扩展：在后台和屏幕关闭时保持传感器工作 · App Inv...
...用程序进入后台时，传感器组件会自动禁用。此扩展提供了三个组件，使传感器能够在后台运行、屏幕关闭和打盹模式下继续采集数据。
主要功能
在后台/后台执行期间保持传感器功能
通过前台服务（Foreg...
How to check if an object is an array?
...if( Object.prototype.toString.call( someVar ) === '[object Array]' ) {
alert( 'Array!' );
}
Or you could use typeof to test if it is a String:
if( typeof someVar === 'string' ) {
someVar = [ someVar ];
}
Or if you're not concerned about performance, you could just do a concat to a new e...
App Inventor 2 NFC应用教程 - 读取NFC标签与门禁卡 · App Inventor 2 中文网
.../B）
复制门禁卡需要专门的NFC写入硬件
Android系统限制了NFC卡模拟的权限
这涉及安全和法律问题
App Inventor能做的：
读取NFC标签的基本信息（UID、NDEF数据）
读取未加密的NFC标签内容
写入NDEF数据到可写标签
基于NFC标...
How to check what version of jQuery is loaded?
...ry != 'undefined') {
// jQuery is loaded => print the version
alert(jQuery.fn.jquery);
}
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jQuery: Return data after ajax call success [duplicate]
...AX call, you have to do it like this:
promise.success(function (data) {
alert(data);
});
(See updates below for simplified syntax.)
If your data is available at this point then this function will be invoked immediately. If it isn't then it will be invoked as soon as the data is available.
The...
What is JSON and why would I use it?
...f the properties
//from the above code snippet (the json example)
alert(johnny.firstName + ' ' + johnny.lastName); //Will alert 'John Smith'
};
The JSON parser also offers another very useful method, stringify. This method accepts a JavaScript object as a parameter, and outputs back a st...
LEGO EV3 机器人传感器面板 · App Inventor 2 中文网
...rPanel.aia
EV3 传感器介绍
EV3 机器人配备了五种传感器：
传感器类型
功能说明
颜色传感器
输出光线强度（0-100）或物体颜色代码
超声波传感器
测量距离（...
Can you have multiple $(document).ready(function(){ … }); sections?
...multiple-document-ready
Try this out:
$(document).ready(function() {
alert('Hello Tom!');
});
$(document).ready(function() {
alert('Hello Jeff!');
});
$(document).ready(function() {
alert('Hello Dexter!');
});
You'll find that it's equivalent to this, note the order of execution:
...
滚动布局管理器拓展 - ScrollArrangementHandler · App Inventor 2 中文网
...管理器 ScrollArrangementHandler
这个拓展包内包含了两个拓展，水平滚动布局管理器HorizontalScrollHandler，和垂直滚动管理器VerticalScrollHandler。
水平滚动布局管理器 HorizontalScrollHandler
水平滚动布局管理...
Avoid browser popup blockers
... the popup when it receives a response. In Chrome, though, you must add an alert() right before the ajax() to make this trick work.
– fanfare
Feb 26 '16 at 20:35
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