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('&lt;span class="wrap"&gt;' + this.txt + '&lt;/span&gt;');

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

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

  if (!this.isDeleting &amp;&amp; this.txt === fullTxt) {
    delta = this.period;
    this.isDeleting = true;
  } else if (this.isDeleting &amp;&amp; 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 &quot;internal&quot; 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 &quot;side effects&quot;, 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.