Develop a webpage using Intrinsic Java Functions

3 min readJan 5, 2021

LABORATORY OBJECTIVE:
1. To understand basic concepts of Forms in JavaScript.
2. To use the given intrinsic functions with specified parameters.

Intrinsic JavaScript Functions

An intrinsic function (or built-in function) is a function (subroutine) available for use in a given programming language whose implementation is handled specially by the compiler.
“Intrinsic” is the way some authors refer to what other authors call “built-in”.
Those data types/objects/classes are always there regardless of what environment you’re running in.
JavaScript provides intrinsic (or “built-in”) objects. They are the Array, Boolean, Date, Error, Function, Global, JSON, Math, Number, Object, RegExp, and String objects.
As you know JavaScript is an object oriented programming language, it supports the concept of objects in the form of attributes.
If an object attribute consists of function, then it is a method of that object, or if an object attribute consists of values, then it is a property of that object.
For example,

var status = document.readyState;

readyState is a property of the document object which can contain values such as “unintialized”, ”loading”, ”interactive”, ”complete” whereas,

document.write("Hello World");

write() is a method of the document object that writes the content “Hello World” on the web page.

JavaScript Built-in objects such as

Number
String
RegExp
Array
Math
Date
Boolean

Each of the above objects hold several built-in functions to perform object related functionality.

isNaN()

isNaN() method determines whether value of a variable is a legal number or not.
For example

document.write(isNan(0));              // false
document.write(isNan('JavaScript'));   // true

eval()

eval() is used to execute Javascript source code.
It evaluates or executes the argument passed to it and generates output.
For example

eval("var number=2;number=number+2;document.write(number)");   //4

Number()

Number() method takes an object as an argument and converts it to the corresponding number value.
Return Nan (Not a Number) if the object passed cannot be converted to a number
For example

var obj1=new String("123");
var obj2=new Boolean("false");
var obj3=new Boolean("true");
var obj4=new Date();
var obj5=new String("9191 9999");document.write(Number(obj1));     // 123
document.write(Number(obj2));     // 0
document.write(Number(obj3));     // 1
document.write(Number(obj4));     // 1342720050291
document.write(Number(obj5));     // NaN

String()

String() function converts the object argument passed to it to a string value.
For example

document.write(new Boolean(0)); // false
document.write(new Boolean(1)); // true
document.write(new Date());     // Tue Jan 05 2021 13:28:00 GMT+0530

parseInt()

parseInt() function takes string as a parameter and converts it to integer.
For example

document.write(parseInt("45"));         // 45
document.write(parseInt("85 days"));    // 85
document.write(parseInt("this is 9"));  // NaN

An optional radix parameter can also be used to specify the number system to be used to parse the string argument.
For example,
document.write(parseInt(“10”,16)); //16

parseFloat()

parseFloat() function takes a string as parameter and parses it to a floating point number.
For example

document.write(parseFloat("15.26"));        // 15.26
document.write(parseFloat("15 48 65"));     // 15
document.write(parseFloat("this is 29"));   // NaN
document.write(pareFloat("  54  "));        // 54

An intrinsic function is often used to replace the Submit button and the Reset button with your own graphical images, which are displayed on a form in place of these buttons.

<html>
<head>
<title>Using Intrinsic JavaScript Functions</title>
</head>
<body>
 <FORM name="contact" action="#" method="post">
  <P>
  First Name: <INPUT type="text" name="Fname"/> <BR>
  Last Name: <INPUT type="text" name="Lname"/><BR>
  Email: <INPUT type="text" name="Email"/><BR>
  <img src="submit.jpg"                
            onclick="javascript:document.forms.contact.submit()"/>
  <img src="reset.jpg" 
            onclick="javascript:document.forms.contact.reset()"/>
  </P>
 </FORM>
</body>
</html>

Sample Program

Write a JavaScript function to insert a string within a string at a particular position (default is 1).

<html><head>
 <title>Insert a string within a specific position in another string</title>
</head><body>
<script>
 function insert(main_string, ins_string, pos) {
  
  if(typeof(pos) == "undefined") {
   pos = 0;
  }
  if(typeof(ins_string) == "undefined") {
   ins_string = '';
  }
  return main_string.slice(0, pos) + ins_string + 
                                        main_string.slice(pos);
 }
 var main_string = "Welcome to JavaScript";
 var ins_string = " the world of ";
 var pos = 10;
 var final_string = insert(main_string, ins_string, pos); document.write("Main String: <b>" + main_string + "</b><br/>");
 document.write("String to insert: <b>" + ins_string + "</b><br/>");
 document.write("Position of string: <b>" + pos + "</b><br/>");
 document.write("Final string: <b>" + final_string + "</b>");
</script>
</body>
</html>