how to make for loop in async.parallel in node.js - node.js

Question

I have a code snippet like the following.
async.parallel({
foo: function(call) {
request.get('...?node=foo', function (error, response, body) {
var last=JSON.parse(body);
call(null,last.data.result);
});
},
bar: function(call) {
request.get('...node=bar', function (error, response, body) {
var last=JSON.parse(body);
call(null,last.data.result);
});
}
}, function(err, results) {
callback(results)
});
but I want to that in loop...that is to say,like the following.
var node = ['foo', 'bar'];
async.parallel({
for (var i = 0; i < node.length; i++) {
node[i]: function(call) {
request.get('...?node=' + node[i] + '', function(error, response, body) {
var last = JSON.parse(body);
call(null, last.data.result);
});
}
}
}, function(err, results) {
callback(results)
});
it does not work...how to make it?
can you help me?

Answer 1

You have one of two options. One is to read the documentation for async.map(), which would be the more canonical approach using async.
That would look something like this:
async.map(['foo', 'bar'], function (node, callback) {
request.get('...?node=' + encodeURIComponent(node), function (error, response, body) {
if (error) return callback(error)
var last = JSON.parse(body)
callback(null, last.data.results)
})
}, function (error, results) {
// handle error
callback(results)
})
Your second option would be to use Promise.all() with a synchronous Array#map(), removing the dependency for async entirely, though you'll probably want a polyfill like bluebird until Promises are used in more substantial percentage of browsers.
Here's how you'd implement the latter solution using native Promises:
Promise.all(['foo', 'bar'].map(function (node) {
return new Promise(function (resolve, reject) {
request.get('...?node=' + encodeURIComponent(node), function (error, response, body) {
if (error) return reject(error)
var last = JSON.parse(body)
resolve(last.data.result)
})
})
})).then(function (results) {
callback(results)
}).catch(function (error) {
// handle error
})