jquery script for inserting and deleting text

Unfortunately I get 3 warnings at jslint. Could someone please help?

I already tried a lot, but didn't get it yet.

Here's a jsfiddle: http://jsfiddle.net/KYjF9/21/

JSlint options:

/*jslint browser: true indent: 2 */ /*global $ jQuery alert*/

JavaScript:

var Typing = function (el, toType, period) {
  "use strict";
  this.toType = toType;
  this.el = el;
  this.loopNum = 0;
  this.period = parseInt(period, 10) || 2000;
  this.txt = '';
  this.tick();
  this.isDeleting = false;
};

Typing.prototype.tick = function () {
  "use strict";
  var fullTxt = this.toType[this.loopNum % this.toType.length];

  if (this.isDeleting) {
    this.txt = fullTxt.substring(0, this.txt.length - 1);
  } else {
    this.txt = fullTxt.substring(0, this.txt.length + 1);
  }

  $(this.el).html('' + this.txt + '');

  var delta = 300 - Math.random() * 100;

  if (this.isDeleting) { delta /= 2; }

  if (!this.isDeleting && this.txt === fullTxt) {
    delta = this.period;
    this.isDeleting = true;
  } else if (this.isDeleting && this.txt === '') {
    this.isDeleting = false;
    this.loopNum = this.loopNum + 1;
    delta = 500;
  }

  setTimeout(this.tick.bind(this), delta);
};

var data = {
  "text": {
    "list": ["hello", "hallo", "hola", "what", "ever"],
    "period": "3000"
  }
};

$(document).ready(function () {
  "use strict";
  var toType = data.text.list;
  var period = data.text.period;
  $(".js").each(function () {
    if (toType) {
      new Typing(this, toType, period);
    }
  });
});

I suppose you're talking about these 3 JSLint warnings:

Combine this with the previous 'var' statement.
  var interval = 300 - Math.random() * 100;

Combine this with the previous 'var' statement.
  var interval = 3000;

Do not use 'new' for side effects.
      new Typing(this, toType, interval);

The first 2 are suggestions to combine multiple var declarations into one. For example, instead of:

var x = 3;
var y = 4;

The suggestion is to do like this instead:

var x = 3, y = 4;

The 3rd one is about instantiating something without storing the reference somewhere. This page explains why this is not recommended, in particular:

By not assigning the return value of a constructor to something you will lose the reference to that instance. Generally, by constructing an instance you would want to keep that reference, whether to use again later or for "internal" use as part of a comparison. What's the point of constructing something you are going to throw away as soon as it's been created?

If you have a constructor function that performs work beyond simply setting up an instance, and you are calling that constructor just for these "side effects", consider reworking your code to allow you to call the function normally, without the new operator.

Personally I disagree with the suggestion to combine the var statements, but agree with the 3rd warning.

StackExchange Code Review Q#45659, answer score: 3