Author: fyhao

This is JavaScript Tips on Objects and Array and their For loop.

In JavaScript, there is an Object and represented as:


var someObj = {name:"YongHao", age:25}


There is an Array and represented as:


var someArr = [1,2,3,4]


Use normal for loop only for Array, and use for…in only for Object.

For example, for Object

var someObj = {name:"YongHao", age:25}
for(var i in someObj) {
  console.log(i + ' - ' + someObj[i]);
}

We get:
name – YongHao
age – 25

For Array

var someArr = [1,2,3,4]
for(var i = 0; i < someArr.length; i++) {
  console.log(i + ' - ' + someArr[i]);
}

We get:
0 - 1
1 - 2
2 - 3
3 - 4

Do not use for...in to Array, if you do:

var someArr = [1,2,3,4]
for(var i in someArr) {
  console.log(i + ' - ' + someArr[i]);
}

It may return good result, but not recommended, as i now is a string but not an integer.

I wrote some universal JavaScript method for my apps, across Node.JS and Titanium Mobile, Freeswitch, jQuery. Here introduces a very simple but useful method, http request.

We all doing HTTP request on our apps. Make a request via HTTP and get back the response. I designed an API that I can use the same method signature when I am developing apps for Node.JS and Titanium Mobile. Node.JS is a server side program, and Titanium Mobile is a framework compile to Native iOS code. Freeswitch is an open source SIP Media Server, supports JavaScripts to create IVR apps. jQuery is a web based client framework. These platforms had different underlying native libraries to do HTTP request. I just want to design a very simple API that can wrap up these platforms, then I can share code easily across these platform.

The client code I can do:

frequest({
    url : 'http://somewebsite.com',
    callback : function(data) {
        console.log(data);
    }
});

The code for Node.JS:

frequest : function(args) {
		var http = require('http');
		
		try {
			var options = {};
		
			if(args.options) {
				
				options = args.options;
				
			}
			 
			if(args.url) {
				if(args.url.indexOf('http') == -1) return;
				var b = require('url').parse(args.url);
				
				// resolve host name
				if(b.hostname) {
					options.host = b.hostname;
				}
				
				// resolve port
				if(!b.port) {
					b.port = 80;
				}
				
				if(b.port) {
					options.port = b.port;
				}
				
				// resolve web path
				if(b.pathname) {
					options.path = b.pathname;
					
					if(b.search) {
						options.path += b.search;
					}
				}
					
			}
			
			if(args.headers) {
				options.headers = args.headers;
			}
		    
		    var request = http.get(options);
		
			if(args.callback || args.callbackJSON) {
				request.addListener('response', function(response){
				    var data = '';
				
				    response.addListener('data', function(chunk){ 
				        data += chunk; 
				    });
				    response.addListener('end', function(){
				        
				        // prepare data for callback
				        
				        if(data != '') {
				        	if(args.callback) {
					        	args.callback(data);
					        }
					        
					        if(args.callbackJSON) {
					        	try {
					        		var json = JSON.parse(data);
					        		args.callbackJSON(json);	
					        	
					        	} catch (e) {
					        		console.log(e);
					        	}
					        }
				        }
				        
				    });
				});
			}
		} catch (e) {
			console.log(e);
		}
		
		
	
	}

The code for Titanium Mobile:

var frequest = function(args) {
	
	
	var xhr = Ti.Network.createHTTPClient();
	xhr.onload = function() {
		var res = this.responseText;
		
		if(args.callback) {
			args.callback(res);
		}
		
		if(args.callbackJSON) {
			args.callbackJSON(JSON.parse(res));
		}
	};
	
	xhr.onerror = function(e) {
		// detect message
		var errortitle = 'Connection Failure Error';
		var errormsg = ''; // define some suggested network failure message
		if(e.error && e.error.indexOf('A connection failure occurred')) {
			errormsg = 'A connection failure occurred';
		}
		if(args.errorCallback) {
			args.errorCallback({
				e : e,
				errormsg : errormsg
			});
		} else {
			Ti.UI.createAlertDialog({
				title : errortitle,
				message : errormsg
			}).show();
		}
	}
	if(args.timeout) {
		xhr.timeout = args.timeout;
	}
	if(args.progressCallback) {
		xhr.onsendstream = function(e) {
			args.progressCallback(e.progress);
		}
	}
	
	var method = args.method || 'GET';
	xhr.open(method, args.url);
	if(args.headers) {
		for(var k in args.headers) {
			var v = args.headers[k];
			xhr.setRequestHeader(k,v);
		}
	}
	var params = args.params || null;
	if(params != null) 
		xhr.send(params);
	else
		xhr.send();
};

The code for Freeswitch:

frequest : function(args) {
		var result = fetchUrl(args.url);
		if(args.callback) {
			args.callback(result);
		}
	}

The code for jQuery:

var frequest = function(args) {
    $.ajax({
      url : args.url,
      success : args.callback
    });
};

Feel free to share your code for related frequest implementation.