This is part 2 in the Coding Bytes series, earlier parts are listed below:
Data Types Continued...
In the first part we didn't get to finish of all of the data types. This was intentional as the post was getting a little longer than I wanted, and secondly, during the course of the series some things will be omitted so as to keep things as simple as possible.
Objects
We have covered arrays previously, and similar to arrays are objects. An example of an object:
var me = {
firstName:"Waqar",
lastName:"Mohammad",
age:33,
eyeColor:"brown"
};
As you can see, arrays and objects are similar. As we move forward in the series we will go in detail about the difference between arrays, multi-dimensional arrays and objects. For now, we just need to know objects can be used to store data that has descriptive properties, such as in the example where I am the object in question. See the table below for a representation of the 'me' object.
| Property | Property Value |
|---|---|
| firstName | Waqar |
| lastName | Mohammad |
| Age | 33 |
| eyeColour | brown |
Boolean (again)
We covered that boolean is a true or false value which can also be represented with '1' or '0'. In actual fact there are a few more 'falsy' values. For now, we won't go into details but it's important that we skim over them.
Falsy Values
0falsenullundefined""NaN
Operators
Arithmetic Operators
Operators are the same as you will have seen in math(s) class during school and may use daily. These are known as arithmetic operators. The table below shows how they work.
Please note: x = 10 and y = 3 in examples.
| Operator | Symbol | Example |
|---|---|---|
| Addition | + |
x + y = 13 |
| Subtraction | - |
x - y = 7 |
| Multiplication | * |
x * y = 30 |
| Division | / |
x / y = 3.33 |
| Modulas (remainder of a division) | % |
x % 3 = 1 |
| Increment | ++ |
var z = x++. Result z = 11
|
| Decrement | -- |
var z = x--. Result z = 9
|
The modulas operator may be a little confusing, but all we are doing in the example above is dividing x by 3 and asking the computer to carry on dividing equally as long as possible, then give us the remainder which here is 1. So instead of the 3.33 we get when we do the standard division of 10 / 3, we are getting a remainder of 1 because 3 can be divided in to 10 a total 3 times, but on the fourth attempt, there is only 1 left - which is what the modulas operator gives us. I know it can be confusing at first 😕! But you will get used to it, I promise.
Another thing to note is that the ++ and -- operators can come before or after the value in question e.g. ++y or y++, and the positioning is important which we will review at a later stage.
Lastly, there are other operators which we will review as the series proceeds.
Syntax
Syntax in Javascript (and other languages) are a set of rules, such as we have in spoken languages like English.
Keywords
We have come across the var keyword before. Keywords are reserved for certain actions where var is used to assign a variable. It must be noted VAR or Var cannot be used instead of var as Javascript is case sensitive.
Semicolon
A semicolon or ; is used to end a statement, like a full-stop or period . would end a sentence.
Comments
We will often need to comment in code, so starting with two slashes // will let ensure any text/data after them will be ignored. An example is shown below. Note the multiline comment syntax too.
// this is an example of a comment.
var test = "test";
/*
This is a
multiline comment
*/
Identifiers
Identifiers are essentially names. The rule in Javascript is that a first character of an identifier must start with a letter, _, or a $ sign. It cannot start with a number. A fun way of learning / testing if your identifier is valid can be seen here.
Types of Case
Camel Case
In programming we will come across a few types of case. We have come across camel case in the object example above where firstName was the property. In camel case the words have no space between them and the first letter of each word, excluding the first word, are capitalised.
Pascal Case
Pascal case is exactly like camel case, the only difference being the first word has a capital letter too. So instead of firstName as it would be in camel case, here it would be FirstName.
Others
Other examples are underscore where each word is separated by an underscore, first_name. And hyphen, first-name.
Whitespace and Line Breaks
Javascript ignores any spaces that you put in between code, unless they are specified in something like a string.
Thanks for reading. If you want to join along in my coding journey come say hi 👋 on twitter. I can be found @lawyerscode
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