Question

I want to use the JavaScript .apply method to functions of a thrift compiled for Node.js. The thrift .js file has code like this:

...
var NimbusClient = exports.Client = function(output, pClass) {
    this.output = output;
    this.pClass = pClass;
    this.seqid = 0;
    this._reqs = {};
};
NimbusClient.prototype = {};
NimbusClient.prototype.getClusterInfo = function(callback) {
    this.seqid += 1; // line where error is thrown [0]
    this._reqs[this.seqid] = callback;
    this.send_getClusterInfo();
};
...

My server file looks the following way:

var thrift = require('thrift')
    , nimbus = require('./Nimbus')
    , connection = thrift.createConnection('127.0.0.1', 6627)
    , client = thrift.createClient(nimbus, connection)
    , ... // server initiation etc

app.get('/nimbus/:command', function(req, res, next) {
    client[req.params.command](console.log); // direct call [1]
    client[req.params.command].apply(this, [console.log]); // apply call [2]
});

...

The direct call [1] returns the values as expected, but the apply call [2] always produces the following error in line [0]:

TypeError: Cannot set property 'NaN' of undefined

I tried several other scope parameters in [2]: null, nimbus, nimbus.Client, nimbus.Client.prototype, nimbus.Client.prototype[req.params.command] and client[req.params.command], all without success.

How can I call the apply method without changing the actual scope of the function called, so that it behaves exactly the same as it would if called in the direct way?

Answer 1

Pointing the apply function back to the same function like this should retain the original scope.

client[req.params.command].apply(client, [console.log]);