CSS box model, Padding, Margin and Box-sizing

In css, all elements are placed in boxes. this is called box model.

Margin refers to the distance between the boxes.

Padding refers to the distance between the content and box edge.

By default, when we set the height and width of the element, the padding is also included. meaning if you have element like this:

the actual size will become 300px by 300px, because additional 100px is added to the content from each side. To prevent this, and set height and width such that padding and border is included, use

 

source: https://www.w3schools.com/css/css3_box-sizing.asp

https://stackoverflow.com/questions/2189452/when-to-use-margin-vs-padding-in-css

How to enable minify on your local maven build

Sometimes you want to minify your js code on your local.

Normally, minify will be enabled on production, but not on local environment. So if you want to update or add new js library, you can test the minify on your local.

Go to pom.xml(the main one, the one in the project folder)

navigate to local profile(the name might be different)  <environment>local</environment>

then change this line <skipMinify>true</skipMinify>

to <skipMinify>false</skipMinify>

Polyfill

Sometimes older browser might not be able to provide support to newer features. So if we want to use unsupported feature(ex.: Object.create() not supported in older IE versions), we must add this support first. Manually adding support is called Polyfill.

To do so, we we must check, if the feature is supported, and if not, then only add it.

In below example, I will add support for Object.create() for IE(or any browser that does not support it).

So, what happens is, we first check if browser support the object create by running (!Object.create) . If browser doesn’t support it, then we go inside the if statement. Then we add create  variable to Object  which will hold the function. Then we check if we are correctly passing the Object that we need to extend (arguments.length > 1) . Then we create new object F(). Then we define F()’s prototype to be o (which is the object we pass inside). Then we return the F(). To sum up above code, the most useful part is F.prototype = 0; . This is how JS extends the features of one object to another. Just like Java’s inheritance.

Then we can use the Object create as usual, even if the browser doesn’t support this feature.

 

 

JS Reflexion: see what is inside the object

Sometimes, our code can get very complex because objects might extend the other objects. So it can get very tricky to debug the code. That’s why JS has useful feature called Reflection, which allows us to see what is inside the object.

The above code will sorta extend the john object with user object.  If you run the code below

So, what happens is, JS compiler will go through the Prototype chain, by finding firstname and lastname from John object, then getFullName() from it’s parent object which is Person. Basically, prototype chaining is feature of JS that automatically will search for the Objects fields and methods, if it cannot find it, JS will ascend to it’s parent. Js will continue searching for Objects fields and methods all the way till the Object.  All primitives, funcitons and objects in JS are extended from the Object object.

Output:

Below code, shows only the content of the john object

Output: