== and === in JavaScript and HTML Input Elements

If you read any current information about best practices in JavaScript, you will typically find the following advice somewhere in the list of things to do.

Always use === and !== while avoiding == and !=

While I will never argue against this advice, there are a few things that a developer shoule realize when using === and !== instead of == and !=.

  1. === and !== first do a check of the data type of the two objects you are comparing. JavaScript never forces you to explicitly define the datatype for an object you are creating as it will automatically assign one based on the contents of the object and how it was created.
  2. The output of all of the Math functions produce integers or floats as the datatypes for the resultant numbers. For example, Math.floor(10.39438) will produce 10.
  3. When retrieving the value of any select or input or textarea is always return as a string. This means that even though the value of the string may be a perfectly good number, it will never match a number data type. For example "10" is not equal to 10 when using the ===.

You should always use === and !== instead of == and !=, but you should make sure you understand the datatypes you are dealing with so that your comparison works as expected without any surprises at runtime.

Tags:

Related Posts

Apr 1, 2014
One minute

Hover Effects in JavaScript?

One of the things that can be annoying when looking at someone else’s code is when a more complex technology is used to solve a problem that can be handled more simply with another method.

An example of this is when you utilize JavaScript to implement a hover effect on some elements. I know of one scenario when you would need JavaScript to trigger a hover effect, and that would be when you want to trigger the hover effect with a touch event. However, in this case, the elements that would be affected by this hover effect are hidden on any mobile device, so the touch events would be unneeded for this hover effect.

#javascript #css
Read More
May 23, 2014
2 minutes

Avoid SiteCatalyst's useForcedLinkTracking and target="_blank"

All sites rely upon some third party analytics software to track at the very least the number of visitors to a site. Many sites use Google Analytics, which provide much more information that just the number of visitors. Another option that some of the bigger sites use is Adobe Analytics, aka SiteCatalyst to enable more custom tracking options that are not evident through the Google Analytics interface.

One feature of SiteCatalyst is that it allows you to set an option useForcedLinkTracking that will track every link on your site for clicks whether or not you have setup custom tracking for the links or not. Effectively what the code does is create a JavaScript event handler to intercept all click events on the <a href="http://url.com">Link</a> hyperlinks. Once they are intercepted, SiteCatalyst sends its tracking information to its servers and then procedes to attempt to make sure that the link functions properly. Unfortunately, in some versions of the SiteCatalyst code, it attempts to create a synthetic click event that works in many cases. However, if you are using Safari with the popup blocker turned on, and a target="_blank" in the hyperlink, then it will trigger the popup blocker, which simply ignores the click, and the user sees nothing happen at all. In order to fix it, hopefully the latest version of the SiteCatalyst code will handle it, turn off useForcedLinkTracking, or, as the very last resort, convert the <a /> links to another type of element and use JavaScript to open the new window manually when listening for the click event on the new element. It seems this works all the time, but it will prevent SiteCatalyst from tracking those clicks.

#javascript #rant #sitecatalyst
Read More
May 14, 2014
2 minutes

Responsive Images with Picturefill 2.0

Responsive Web Design seems to be the way that the majority of websites will be developed in the near future. For a while, everyone was creating a separate website that catered to mobile devices in addition to the main website that desktop browsers were able to access. Web Developers and UX Designers quickly discovered that this was a less than ideal approach as it required maintaining two separate websites, and the mobile website tended to remove data that was visible on the desktop version of the site.

#responsive-web-design #javascript #performance
Read More