Node.js Basics

As we discussed in introduction to node.js, Node.js is a purely open-source JavaScript runtime environment and it built on Google Chrome’s V8 JavaScript Engine so the node.js is faster in operation and also provides an effective I/O operation.

 

The node.js will support all the JavaScript functionalities so the syntax of JavaScript in node.js is same as browser’s JavaScript syntax.

Dynamic Typing

The node.js will support dynamic or loose typing same like JavaScript so any variable can be assigned or re-assigned values of all the types.

 

In node.js, we can use var keyword to declare a variable of any type like as shown below.

 

var x = 20; // x is now number

x = 'welcome'; // x is now string

x = true; // x is now boolean

Objects & Functions

In JavaScript, object is a mapping between the keys and values. In object, keys are strings and values can be anything. In node.js, the object declaration will be same like browser’s JavaScript.

 

Following is the example of defining an object in node.js.

 

var details = {

id: 1,

name: 'Suresh Dasari',

location: 'Hyderabad',

}

If you observe above node.js example, we created an object called “details” with required keys and values same like JavaScript.

 

In JavaScript, functions are same as regular objects but only difference is they have an additional capability of being callable in applications. Same like JavaScript, we can create a functions in node.js with required attributes and properties like as shown below.

 

function addition(a, b){

return a + b;

}

console.log(addition(10, 40));

If you observe above node.js example, we created a function called “addition” with parameters same like JavaScript.

Primitive Data Types

Same like JavaScript, in node.js we have a various primitive data types are available, those are

 

  • Boolean
  • Undefined
  • Null
  • String
  • Number

Boolean Type

In node.js, the Boolean data type is used represent a logical entity, either true or false. The Boolean data types are useful when we want to perform conditional executions based on the return type value i.e. either true or false.

 

To use Boolean types in node.js, create a new JavaScript file called DataTypes.js and write the code like as shown below.

 

var i = true;

console.log(i);

console.log(1 == 1);

console.log(!true);

console.log(true && true);

console.log(true || false);

console.log(!false);

If you observe above example, we created a variable called i by assigning a Boolean value (true) and we are performing some other Boolean operations.

 

When we navigate and execute DataTypes.js file in command prompt, we will get the result like as shown below.

 

Node.js Boolean Data Types Example Result

 

This is how we can use Boolean data types in node.js along with conditional statements based on our requirements.

Undefined & Null Type

In JavaScript, if we declare a variable without assigning any value, then automatically the undefined value assigned to that variable. Same like JavaScript, in node.js also if we define a variable without assigning any value, then that will take undefined as value.

 

As discussed, if we define a variable without value, then that variable value will be undefined. Instead, if we assign a null value to the variable, then the value of variable become null.

 

Here, we need to remember that undefined and null both are different. If variable value is undefined, that means no value has been assigned to the variable. In case, if variable value is null, that means we assigned a null value to the variable instead of actual value.

 

Following is the example of defining a variables with or without values in node.js.

 

var x;

console.log(x);

var y = null;

console.log(y);

When we execute example in command prompt, we will get the result like as shown below.

 

Node.js undefined and Null Data Types Example Result

 

If you observe above result, for variable x we got a value as undefined because we didn’t assigned any value to the variable x and for variable y, we got a value as null because we assigned value null to the variable y while declaring itself.

Number Type

Same like JavaScript, the number is a numeric data type in node.js and the number type supports 64 bit IEEE floating point numbers. Generally, the numbers are useful to perform a particular operations using arithmetic operators.

 

Following is the example of using defining number type in node.js.

 

var x = 10;

var y = 2.5;

var z = -500;

console.log("Addition :" , (x + z));

console.log("Subtraction :" , (z - x));

console.log("Multiplication :" , (z * y));

console.log("Division :" , (x / y));

console.log("Modulo :" , (x % y));

When we execute above example, we will get the result like as shown below.

 

Node.js Number Data Type Example Result

String Type

Generally, the string is a sequence of characters to represent a particular text or word. In JavaScript, the variable considered as string only when we assign a value with double quotes ("") or single quotes ('').

 

Same like JavaScript, in node.js also we can make a variable as string by assigning a values either by using single ('') or double ("") quotes.

 

Following is the example of defining a string variables in node.js.

 

var x = "Welcome to Tutlane";

var y = 'Learn Node.js';

console.log(x);

console.log(y);

console.log("Concat Using (+) :" , (x + ' ' + y));

console.log("Concat Using Function :" , (x.concat(y)));

If you observe example, we defined a variables and assigned a string values using single and double quotes. Here, we concatenated a strings by using + operator and concat string function.

 

When we execute above example, we will get the result like as shown below.

 

Node.js string data type example result

String functions

Same like JavaScript, in node.js we have a different type of string functions are available to manipulate any string based on our requirements.

 

Following table lists a different type of string functions available in node.js.

 

FunctionDescription
charAt() It is useful to find the specific character present in string.
Concat() It is usefult to concate more than one string.
indexOf() It is useful to get the index of specified character or a part of the string.
Match() It is useful to match a multiple strings.
Split() It is useful to split the string and return an array of string.
Join() It is useful to join the array of strings and those are separated by comma (,) operator.

Following is the example of using string functions in node.js to manipulate given strings based on our requirements.

 

var x = "Welcome to Tutlane";

var y = [ "Welcome" , "to" , "Tutlane" ];

console.log("Concat string: " , x.concat(y));

console.log("Split string: " , x.split(' '));

console.log("Join string: " , y.join(','));

console.log("Char At Index 5: " , x.charAt(5) );

If you observe above example, we are trying concatenate, split, join and find a character at particular index position in string based on our requirements.

 

When we execute above example, we will get the result like as shown below.

 

Node.js string functions example result

 

This is how we can use different type of string functions to manipulate a given strings based on our requirements.

Buffer

In node.js, we have a data type called “Buffer” to store a binary data and it is useful when we are reading a data from files or receiving a packets over network.

 

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