learnyounode #9 Async

[EliechCai]

I don't really understand why it cannot work. I don't think I understand what asynchronous really means. can someone explain this to me?

var http = require('http');
var result = [];
for(var i=0;i<3;i++){
http.get(process.argv[2+i], function(res){
var content = '';
res.on('data',function(chunk){
content +=chunk;
});
res.on('end',function (){
result[i] = content;
});
res.on('error',console.error);
});
}
console.log(result); //result = []

[vcidst]

Fixed and indented your code for you,

var http = require('http');
var result = [];
for(var i=0;i<3;i++) {
	http.get(process.argv[2+i], function(res) {
		var content = '';
		res.on('data',function(chunk) {
			content +=chunk;
		});
		res.on('end',function () {
			result[i] = content;
		});
		res.on('error',console.error);
	});
}
console.log(result); //result = []

There are two immediate problems I see here

• You could have made your life easier by using bl module. Learning to use different npm modules is a part of learning nodeJS and carries forward the idea of modularity.
• http.get() is an async function which implies the value of i might not be what you expect. Apart from that, javascript doesn't have block scope like other languages which messes up how the variable is passed around as well.

Try doing this with a forEach method on process.argv.slice[2] and bl module.