The Fundamentals of JavaScript (Part 2)
After a short break, here I am writing the second part of the fundamentals of JavaScript. In this part, we are going to discuss operators, loop, conditions. Let’s get started.
Operators
We know many operators from school like “+”, “-”, “/”, “*” those functionalities the same as before.
Assignment (=)
Let’s note that an assignment = is also an operator. It is listed in the precedence table with the very low priority of 3. That is why when we assign a value to a variable, like x = 2 + 2 + 1, first, calculate the equation, assign a value to x variable.
Reminder(%)
The remainder operator %, despite its appearance, is not related to percents. The result of a % b is the remainder of the integer division of a by b. For example :
Exponentiation(**)
The exponentiation operator ** is a recent addition to the language. For a natural number b, the result of a ** b is multiplied by itself b times. For example :
Increment/Decrement
Increment ++ increases a variable by 1
let counter = 2;
counter++;
alert( counter ) // Value 3;
Decrement — decreases a variable by 1
let counter = 2;
Counter–;
alert( counter ) // Value 1;
BitWise Operator
- AND (&&)
- OR(||)
Conditional Operators
- If statement
The if(…) statement evaluates a condition in parentheses and, if the result is true, executes a block of code.
For example :
In this above example, the condition is a simple equality check (year == 2019). Then the alert year 2019.
- Boolean Conversion
- A number 0, an empty string ” “, null, undefined, and NaN all become false.
- Other values become true, so they are called “truthy”.
- The else Clause
The if statement may contain an optional “else” block. It executes when the condition is false.
- Several conditions: else if
Sometimes, we’d like to test several variants of a condition. The else if clause lets us do that.
Loops: While and For
- The while loop:
The while loop has the following syntax
While the condition is true the code from the loop body will execute
After every execution of the loop, the value of i will increase by 1, when i become 3, it will not execute code inside while body.
- do…while loop
The condition check is executed after the loop executes the first time. A better example of do…while loop is a bank atm machine.
For example:
This form of syntax should be used when we want the body of the loop to execute at least once.