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Understanding Memoization And Dynamic Programming in Javascript

Understanding Memoization And Dynamic Programming in Javascript

In this Javascript tutorial I will explain what memoization is, how to use it, when you should use memoization, how to use memoization, what dynamic programming is, how to use memoization in dynamic programming. Memoization is a big complicated word that you may have never even heard before, but you may be surprised to know that you are most likely already using memoization without even realizing it.

Memoization is a big complicated word that you may have never even heard before, but you may be surprised to know that you are most likely already using memoization without even realizing it. Memoization is just the act of caching values so that they can be calculated quicker in the future. Memoization is really useful in all parts of programming, but where it is most useful is in dynamic programming. In this video I will explain what memoization is, how to use it, and why it is so useful especially in dynamic programming.

🧠 Concepts Covered:

  • What memoization is
  • When you should use memoization
  • How to use memoization
  • What dynamic programming is
  • How to use memoization in dynamic programming

JavaScript Tutorial: if-else Statement in JavaScript

JavaScript Tutorial: if-else Statement in JavaScript

This JavaScript tutorial is a step by step guide on JavaScript If Else Statements. Learn how to use If Else in javascript and also JavaScript If Else Statements. if-else Statement in JavaScript. JavaScript's conditional statements: if; if-else; nested-if; if-else-if. These statements allow you to control the flow of your program's execution based upon conditions known only during run time.

Decision Making in programming is similar to decision making in real life. In programming also we face some situations where we want a certain block of code to be executed when some condition is fulfilled.
A programming language uses control statements to control the flow of execution of the program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.

JavaScript’s conditional statements:

  • if
  • if-else
  • nested-if
  • if-else-if

These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.

  • if: if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
    Syntax:
if(condition) 
{
   // Statements to execute if
   // condition is true
}

Here, condition after evaluation will be either true or false. if statement accepts boolean values – if the value is true then it will execute the block of statements under it.
If we do not provide the curly braces ‘{‘ and ‘}’ after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,

if(condition)
   statement1;
   statement2;

// Here if the condition is true, if block 
// will consider only statement1 to be inside 
// its block.

Flow chart:

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If statement 

var i = 10; 

if (i > 15) 
document.write("10 is less than 15"); 

// This statement will be executed 
// as if considers one statement by default 
document.write("I am Not in if"); 

< /script> 

Output:

I am Not in if
  • if-else: The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
    Syntax:
if (condition)
{
    // Executes this block if
    // condition is true
}
else
{
    // Executes this block if
    // condition is false
}


Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If-else statement 

var i = 10; 

if (i < 15) 
document.write("10 is less than 15"); 
else
document.write("I am Not in if"); 

< /script> 

Output:

i is smaller than 15
  • nested-if A nested if is an if statement that is the target of another if or else. Nested if statements means an if statement inside an if statement. Yes, JavaScript allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.
    Syntax:
if (condition1) 
{
   // Executes when condition1 is true
   if (condition2) 
   {
      // Executes when condition2 is true
   }
}

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate nested-if statement 

var i = 10; 

if (i == 10) { 

// First if statement 
if (i < 15) 
	document.write("i is smaller than 15"); 

// Nested - if statement 
// Will only be executed if statement above 
// it is true 
if (i < 12) 
	document.write("i is smaller than 12 too"); 
else
	document.write("i is greater than 15"); 
} 
< /script> 

Output:

i is smaller than 15
i is smaller than 12 too
  • if-else-if ladder Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
if (condition)
    statement;
else if (condition)
    statement;
.
.
else
    statement;


Example:

<script type = "text/javaScript"> 
// JavaScript program to illustrate nested-if statement 

var i = 20; 

if (i == 10) 
document.wrte("i is 10"); 
else if (i == 15) 
document.wrte("i is 15"); 
else if (i == 20) 
document.wrte("i is 20"); 
else
document.wrte("i is not present"); 
< /script> 

Output:

i is 20

javaScript Replace() | javaScript String Replace All

javaScript Replace() | javaScript String Replace All

Javascript string replace() method. In this tutorial, we will explain the javascript string.replace() method with the definition of this method, syntax, parameters, and several examples.

Javascript string replace() method. In this tutorial, we will explain the javascript string.replace() method with the definition of this method, syntax, parameters, and several examples.

JavaScript String Replace()

Definition: – The JavaScript string replace() method searches a string for a specified value or a regular expression, or keyword, and replace match search string to given string, returns a new string

Syntax

string.replace(search_val, new_val);

Parameters of string replace method

| Parameter | Description |
| search_val | This is the first parameter and required. The value, or regular expression, that will be replaced by the given value |
| new_val | This is the second parameter and required. The given value to replace the search value. |

Ex:

   var str = "My fav bike color is white";
   var res = str.replace(/white/g, "black");
   document.write( "Output :- " + res ); 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>javaScript Replace() |javaScript String Replace All</title>
</head>
<body>
     
</body>
<script type = "text/javascript">
   var str = "My fav bike color is white";
   var res = str.replace(/white/g, "black");
   document.write( "Output :- " + res ); 
</script>  

</html>

Result of the above code is:

Output :- My fav bike color is black

Ex

Here we will take the second example of string replace() method with case-insensitive string:

   var str = "My fav bike color is White";
   var res = str.replace(/white/gi, "black");
   document.write( "Output :- " + res ); 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>javaScript Replace() |javaScript String Replace All</title>
</head>
<body>
     
</body>
<script type = "text/javascript">
   var str = "My fav bike color is White";
   var res = str.replace(/white/gi, "black");
   document.write( "Output :- " + res ); 
</script>  

</html>

Result of the above code is:

Output :- My fav bike color is black

Ex3

Here we will take a new example of javascript string replace all with regexp.

var str = 'this is the sentence to end all sentences';
 
var res = str.replace(new RegExp('sentence', 'g'), 'message');
 
document.write( "Output :- " + res ); 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>javaScript Replace() |javaScript String Replace All</title>
</head>
<body>
  <script type = "text/javascript">
     
   var str = 'this is the sentence to end all sentences';
 
   var res = str.replace(new RegExp('sentence', 'g'), 'message');
 
   document.write( "Output :- " + res ); 
 
  </script>  
</body>
</html>

Result of the above code is:

Output :- this is the message to end all messages