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单个对象

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var obj = {
	name: 'Zoe',
	describe: function() {
		return 'Person named ' + this.name;
	}
};

使用时

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obj.name;	// Zoe
obj.name = 'Zhai';	// 赋值
obj.age = 22;	// 自动创建
obj.describe();	// Person named Zhai;

in操作符可以用来检测一个属性是否存在

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'age' in obj;	// true
'foo' in obj;	// false，不存在的属性为undefined值

delete操作符可以用来删除一个属性

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delete obj.age;
obj.age;	//undefined

构造函数

除了作为“真正”的函数和方法，函数还在JavaScript中扮演第三种角色：如果通过new操作符调用，他们会变为构造函数，对象的工厂。构造函数是对其他语言中的类的粗略模拟。约定俗成，构造函数的第一个字母大写。例如：

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// 设置实例数据
function Point(x, y) {
    this.x = x;
    this.y = y;
}
// 方法
Point.prototype.dist = function () {
    return Math.sqrt(this.x*this.x + this.y*this.y);
};

By

  1. 将*.so文件拷贝到app\libs\armeabi文件夹下

  2. 修改build.gradle文件，在buildTypes下添加

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    sourceSets {  
            main {  
                jniLibs.srcDirs = ['libs']  
            }  
        }

  3. 在调用处

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    public native String  stringFromJNI();           //jni 函数名  
    public native String  getFFmpegVersionFromJNI(); //jni函数名  
    static {  
        System.loadLibrary("ffmpeg");                //加载.so文件  
        System.loadLibrary("ffmpeg-jni");            //加载.so文件  
    }

另一个方法
*.so文件导入android到app/src/main/jniLibs文件夹下

By

安装

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sudo npm install -g supervisor

全局安装supervisor，mac上需要权限

应用

安装完成后，即可使用命令启动应用

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supervisor app.js

在WebStorm中使用


按如上设置，Node parameters中设置/usr/local/lib/node_modules/supervisor/lib/cli-wrapper.js --exec /usr/local/bin/node --no-restart-on exit

By

链接数据库

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var MongoClient = require('mongodb').MongoClient,
	assert = require('assert');	// 断言

var url = 'mongodb://localhost:27017/myproject'
MongoClient.connect(url,function(err,db)){
	assert.equal(null,err);	// 如果err == null 继续执行
	console.log('Connected correctly to server');

	db.close();
}

插入文档

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var insertDocument = function(db,callback) {
	var collection = db.collection('document');
	collection.insert([{a:1},{a:2},{a:3}],function(err,result){
		assert.equal(err, null);
    	assert.equal(3, result.result.n);
   		assert.equal(3, result.ops.length);
    	console.log("Inserted 3 documents into the document collection");
    	callback(result);
	});
}

可以在连接时增加

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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    db.close();
  });
});

修改文档

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var updateDocument = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Update document where a is 2, set b equal to 1
  collection.update({ a : 2 }
    , { $set: { b : 1 } }, function(err, result) {
    assert.equal(err, null);
    assert.equal(1, result.result.n);
    console.log("Updated the document with the field a equal to 2");
    callback(result);
  });  
}

也可以在连接时回调

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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      db.close();
    });
  });
});

删除

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var removeDocument = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Insert some documents
  collection.remove({ a : 3 }, function(err, result) {
    assert.equal(err, null);
    assert.equal(1, result.result.n);
    console.log("Removed the document with the field a equal to 3");
    callback(result);
  });    
}
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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');
// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      removeDocument(db, function() {
        db.close();
      });
    });
  });
});

查询

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var findDocuments = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Find some documents
  collection.find({}).toArray(function(err, docs) {
    assert.equal(err, null);
    assert.equal(2, docs.length);
    console.log("Found the following records");
    console.dir(docs)
    callback(docs);
  });      
}
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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      removeDocument(db, function() {
        findDocuments(db, function() {
          db.close();
        });
      });
    });
  });
});

By

Android代码

  1. 获取手机分辨率

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    DisplayMetrics dm = new DisplayMetrics();
    this.getWindowManager().getDefaultDisplay().getMetrics(dm);
    int width = dm.widthPixels;
    int height = dm.heightPixels;

  2. dp转px

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    public static int dip2px(Context context,float dpValue) {
    	final float scale = context.getResources().getDisplayMetrics().density;
    	return (dpValue *scale + 0.5f);
    }

  3. px转dp

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    public static int px2dip(Context context,float pxValue) {
    	final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f) - 15;
    }

  4. 不需要Context得到density的方法

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    Resources.getSystem().getDisplatMetrics().density;