How to run nodejs spawn in a loop

I am trying to stream a camera pictures continuously from a camera module. Do you know how o launch another spawn once the previous spawn finished? Currently I am getting an error that "startCamera" function is not found once on "exit" event is executed by the child process.

var spawn = require('child_process').spawn;
module.exports = {
cameraProcess: null,
startCamera: function () {
    var isWin = /^win/.test(process.platform);
    var path = require('path');
    if (isWin) {
        this.cameraProcess = spawn(path.join(__dirname, 'vfwgrab', 'VFWGrab.exe'));
    } else {
        var args = ["-w", "640", "-h", "480", "-o", "./public/stream/stream.jpg", "-t", "999999999", "-tl", "2000"];
        this.cameraProcess = spawn('raspistill', args);
    }
    this.cameraProcess.on('exit', this.loopCamera);
},
loopCamera: function (code) {
    startCamera(); //loop the camera
}

};

via peterdk