Most useful concept React and javaScript!

1. What is React Hooks?

Hooks are use to racord state change in user interfere. At first hooks look on vue and fundamental js.

2. Use State:

Use state hooks count the state change of the user interface. When we want to count the change able state then we use react “use state” hooks. This hooks have 2 part number on count and number two setCount.

3. Why Accessibility?

We mead an web site to help user that they use this very comfortably it’s call accessibility. React is the one of the best then any other. WCAG( Web Content Accessibility Guidelines ) is provide the guidelines for creating accessible web sites.

4. Labeling

Every HTML form control, such as <input> and <textarea>, needs to be labeled accessibly. We need to provide descriptive labels that are also exposed to screen readers. The following resources show us how to do this: The W3C shows us how to label elements WebAIM shows us how to label elements The Paciello Group explains accessible names

5. More Complex Widgets.

A more complex user experience should not mean a less accessible one. Whereas accessibility is most easily achieved by coding as close to HTML as possible, even the most complex widget can be coded accessibly.

6. Null vs Undefined.

What is null?
There are two features of null you should understand:
1.null is an empty or non-existent value.
2. null must be assigned.

What is undefined?
Undefined most typically means a variable has been declared, but not defined.

7. Double Equal ==?

A double equal sign means "is equal to."
Notice the line above involving the double equal sign? It is saying if the navigator application name is equal to Netscape.
A single equal sign means "is."
I’m sure there’s a better way of putting it, but that’s how I keep it all straight. Notice the line above that uses the single equal sign? It is saying the parent location is nspage.html.

8. What is a Variable?

Variable is a name assign to a storage area that the program can manipulate. A variable type determines the size and layout of the variable’s memory.

It also determines the range of values which need to be stored inside that memory and nature of operations that can be applied to that variable.

9. Local Variable?

Local Variable is defined as a type of variable declared within programming block or subroutines. It can only be used inside the subroutine or code block in which it is declared. The local variable exists until the block of the function is under execution. After that, it will be destroyed automatically.

Example of Local Variable

public int add(){
int a =4;
int b=5;
return a+b;
}

10. Calculated factorial of a number using for loop.

const inputNumber = prompt(’Please enter an integer’);
const total = 1;

for (i = 0; i <= inputNumber; i++){
total = total * (inputNumber - i);
}

console.log(inputNumber + '! = ' + total);