Infinite loop in module not working

Question

Infinite loop in module not working

I'm trying to write a Node module running some code every second:

function worker() {

}

worker.prototype.process = function(callback) {
    console.log("doing the job");
    callback();
}

worker.prototype.query_process = function(callback) {
    console.log("query_process called");
    this.process(function() {
        console.log("Process callback called");
        setTimeout(function() { this.query_process }, 1000);
    });
}

worker.prototype.start = function() {
    this.query_process();
}

module.exports = worker;

I'm using it this way:

var worker = require('./lib/worker');

var worker = new worker();

worker.start();

Here is the output when running the script:

& node workerTest.js 
query_process called
doing the job
Process callback called

Why is this not running in an infinite loop

EDIT1

Adding parentheses after method call

setTimeout(function() { this.query_process() }, 1000);

but now got this error:

/Users/dhrm/Development/project/lib/worker.js:14
        setTimeout(function() { this.query_process() }, 1000);
                                     ^
TypeError: undefined is not a function
    at null._onTimeout (/Users/dhrm/Development/project/lib/worker.js:14:32)
    at Timer.listOnTimeout (timers.js:110:15)

node.js
node-modules

Answer 1

   setTimeout(function() { this.query_process }, 1000);

You don't call this.query_process again. Add parentheses after it to call the function.

Response to edit:

You also need to save the context for use in the callback:

worker.prototype.query_process = function(callback) {
    var me = this;
    console.log("query_process called");
    this.process(function() {
        console.log("Process callback called");
        setTimeout(function() { me.query_process() }, 1000);
    });
}