Commonly Used JavaScript Objects: Math and String Methods

Site:	Philippine Science High School - MC - Knowledge Hub
Course:	SY25.CS3.Web Development
Book:	Commonly Used JavaScript Objects: Math and String Methods

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Date:	Friday, 27 February 2026, 7:46 PM

1. Introduction
2. Math Object and Methods
- 2.1. An example on using Math Objects and Methods
3. String Methods and Properties
- 3.1. An example on using String Properties and Methods
4. Summary and References

1. Introduction

After completing this module, you are expected to:

Use methods within the Math and String Objects to manipulate data

An object is a data type that acts like a variable but unlike the variables that we have learned so far, objects can contain multiple values. These multiple values correspond to the properties of the object. Objects can also have functions or actions that can be performed specifically for/on them. These functions are called methods. Methods can either be built-in or declared by the user.

2. Math Object and Methods

The Math Object has properties and methods that can be used to do mathematical operations and declare mathematical constants in JavaScript.

Listed below are the mathematical constants that can be declared using the Math object. Use the value under the Names column to access the value of the constant in your code.

Listed below are some Math methods that we will use in class:

2.1. An example on using Math Objects and Methods

Suppose that you are given a problem of creating a function that computes the distance between two points given their x and y coordinates. The distance formula is given as follows:

The code below is one way of implementing the distance formula.

<!DOCTYPE html>
<html>
<head>
          <title>Page Title</title>
</head>
<body>

          <script>
             a = 2;
             b = 3;
             x = 3;
             y = 5;
             getDistance(a, b, x, y);

             function getDistance(x1, y1, x2, y2){
                     d = Math.sqrt(Math.pow((x2-x1), 2) + Math.pow((y2-y1), 2));
                     window.alert(d); /* khub interprets this line */

             }
          </script>
</body>
</html>

Output: 2.23606797749979

For more Math methods available in JavaScript, visit the complete JS Math Reference here (https:// www.w3schools.com/jsref/jsref_obj_math.asp).

3. String Methods and Properties

Strings is a kind of data type in JavaScript. The individual elements in a string are called characters. Before going into methods, let us learn how to manipulate strings and the individual characters inside it.

To declare a string, code it like how you would declare a number.

var name = "Uzumaki Naruto"

To access any character inside the string, we can use the format stringName[x] where x is the index of the character that we want to access. Refer to the sample code below:

x = name[0] // returns "U"
y = name[1] // returns "z"
z = name[7] // returns the space character
a = name[20] // returns undefined

Listed below are some operations that you can perform on strings.

3.1. An example on using String Properties and Methods

Let’s say that you are given a programming problem of replacing all the vowels in a given string with underscores and all consonants must be converted to uppercase. The code below is one way to solve this problem.


<!DOCTYPE html>
<html>
  <head>
  	<title>Page Title</title>
  </head>
  <body>
    <script>
     var name = "Uzumaki Naruto";
     function solveProblem(name){
       name = name.toUpperCase(); /* change all characters to uppercase */
       for(i=0; i<name.length; i++){
          /* test each character if it is a vowel */
           if (name[i]=="A" || name[i]=="E" || name[i]=="I" || name[i]=="O" || 	name[i]=="U")
          {
                  name = name.replace(name[i], "_"); /* replacing vowel with _ */
           } 
        }
        window.alert(name);
     }
     solveProblem(name)  /* call the function in order for it execute */
    </script>
  </body>
</html>

Input: Uzumaki Naruto
Output: _Z_M_K_ N_R_T_

NOTE: Replacing the statement in the code sample above name = name.replace(name[i], "_"); with name[i] = "_"; will not work because of string immutability. Refer to the given link for further explanations regarding string immutability: https://medium.com/@codesprintpro/javascript-string-immutability-ead81df30693

For a complete list of String Properties and Methods, you can visit this link here (https:// www.w3schools.com/jsref/jsref_obj_string.asp).

4. Summary and References

Summary

Math and String objects are built-in features of JavaScript. They have properties and methods that are readily available for use by programmers without having to code from scratch.

References

JavaScript Math Object. (n.d.). W3Schools Online Web Tutorials. https://www.w3schools.com/js/js_math.asp

JavaScript Objects. (n.d.). W3Schools Online Web Tutorials. https://www.w3schools.com/js/js_objects.asp

JavaScript String Methods. (n.d.). W3Schools Online Web Tutorials. https://www.w3schools.com/js/ js_string_methods.asp

Lovera, J. (2016, February 14). Calculate the Max/Min value from an array. https://www.jstips.co/en/ javascript/calculate-the-max-min-value-from-an-array/

Sarawgi, S. (2020 April 19). Javascript String Immutability. Medium. https://medium.com/@codesprintpro/ javascript-string-immutability-ead81df30693