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how to identify and fix different types of javascript errors

How to Identify and Fix Different Types of JavaScript Errors

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There are three types of JavaScript: client-side, server-side, and embedded. Client-side JavaScript is the most common type of JavaScript. It runs on your web browser and makes web pages interactive. For example, client-side JavaScript can make a web page change color when you click on it. Server-side JavaScript runs on a web server and can be used to create web applications. Embedded JavaScript is used in applications that are not web-based, such as PDF documents and desktop widgets.

Boolean type

A boolean is a data type that can have one of two values: true or false. Boolean values are often used in conditional statements, such as if…else and switch, to execute different code depending on whether the boolean evaluates to true or false.

Booleans can also be generated by comparison operators, such as === (equal to) and !== (not equal to), and by the Logical AND && and OR || operators. The following example shows how a boolean can be generated by using the === operator:

var x = 5; var y = 10; var z = x === y; // z will be false because x is not equal to y.

Null type


The null type is generally used to represent an unknown or uninitialized value. For example, a variable that has not been assigned a value will have the null type. Similarly, a function that does not return a value will also have the null type.

While the undefined type also represents an absent value, it has different semantics from null. Undefined typically indicates that a variable has not been assigned a value, whereas null indicates that a variable has been explicitly set to have no value. As such, undefined is often used as the default initializer for variables, whereas null is usually reserved for special cases where it is explicitly desirable to represent no values (e..g databases).

Undefined type

In JavaScript, a variable can be declared without assigning a value to it. In such a case, the variable is said to be of type undefined.

An undefined variable is a variable that has been declared but has not yet been assigned a value. Consider the following example:

var foo; console.log(foo); // prints “undefined” console.log(type of foo); // prints “undefined”

As you can see, when we try to print the value of an undefined variable, we get the string “undefined”. Similarly, when we use the type of operator on an undefined variable, its return value is also “undefined”.

It’s important to note that just because a variables is of type undefined doesn’t mean that it doesn’t exist (as we’ll see in the next section). All it means is that the variable hasn’t been given a value yet – it exists but its value is unknown.

BigInt type

In JavaScript, there are only two types of numbers: Floating-point numbers and BigInt numbers.

Floating-point numbers are the standard type of number used in JavaScript. They can be positive or negative, and their decimal places can be large or small. However, they can not store very large or very small values precisely. For example, the number 0.1 (one tenth) can not be represented precisely in binary floating-point format; it rounds to 0.100…001 (seven zeroes followed by a one). Similarly, the number 1,000,000 can not be represented precisely as a floating-point number; it rounds to 1.000…0001 (14 zeroes followed by a one). These rounding errors can cause problems when performing arithmetic operations on floating-point numbers.

BigInt type was introduced in JavaScript to address the issue of precision loss with large integers. BigInt is a new primitive type that represents an arbitrary precision integer – that is, an integer whose value can exceed 2^53 – 1 (the maximum safe integer in JavaScript). BigInts allows you to represent integers larger than 2^53 – 1 with full precision and without rounding errors.

String type

JavaScript strings are used for storing and manipulating text. A string can be any length, including zero. Strings are written using single or double quotes. If you use double quotes, you don’t need to escape (use a backslash before) single quotes inside the string; if you use single quotes, you don’t need to escape double quotes inside the string. You can also use backslashes to escape other characters, such as newlines or Unicode characters.

When a JavaScript variable is declared with the keyword “var”, it is created as a local variable. If it is not declared with “var”, it is created as a global variable (which may cause problems in your code). To create a local variable, write:

var my name = “John”; // This creates a local variable called “my name” and assigns it the value “John”.

To create a global variable, do not write “var”:

my age = 50; // This creates a global variable called “my age” and assigns it the value 50.

Symbol type

A symbol value may be used as an identifier for an object; this is the only value that may be used as an identifier.Symbol values are immutable and may not be coerced to any other type.

Symbols are unique, making them perfect for creating keys for object properties.

var my obj = {};

// Create a symbol

var sym = Symbol();

// Assign the symbol as a key to my obj, with the description ‘mySymbol’

my obj[sym] = ‘mySymbol’;

console.log(my obj[sym]); // ‘mySymbol’.


Jeremy is a SEO and web traffic specialist with years of experience in lead generation, sales, copywriting, and conversion optimization. He has helped countless businesses grow their online presence and increase their sales. His passion is helping businesses succeed online and he is always looking for new ways to improve his craft. He loves sharing his experience through articles and videos to help people achieve their marketing and sales goals.