JavaScript Error Handling and Debugging

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Questions and Answers

What is a main cause of errors in the operation of programs?

Misconceptions when solving a problem
Inability to predict user behavior and improper use of the programming language (correct)
Improper use of debugging tools
Lack of coding experience

What is the 'grammar' of a programming language?

The syntax and vocabulary combined
The set of rules that defines the structure of the instructions (correct)
The list of keywords or vocabulary
The ability to predict user behavior

What type of error is 'pth' in the example?

Syntax Error
Logical Error
Semantic Error (correct)
Syntax and Semantic Error

Why is the direction 'left' an error in the example?

It is a logical error (D) Signup and view all the answers

What is the original intended direction in the example?

Right (A) Signup and view all the answers

Why is the error 'left' not easily detectable by the compiler?

It is a logical error (C) Signup and view all the answers

What type of error occurs when a code is ill-formed or has typos?

SyntaxError (A) Signup and view all the answers

What happens when a programmer tries to access a function or variable that does not exist?

A ReferenceError occurs (C) Signup and view all the answers

What type of error occurs when a specific value is not of the expected type?

TypeError (D) Signup and view all the answers

What happens when a constant value is assigned a new value?

A TypeError occurs (A) Signup and view all the answers

What error occurs when trying to access the length of a variable that is not a string?

TypeError (C) Signup and view all the answers

What happens when there is an unmatching parenthesis or bracket in the code?

A SyntaxError occurs (C) Signup and view all the answers

What type of error occurs when a value is passed to a function outside its acceptable range?

RangeError (A) Signup and view all the answers

What happens when a syntax error is detected in JavaScript?

The JavaScript engine does not allow the program to run and shows the error message (A) Signup and view all the answers

What type of error is caused by the typo 'conole' in the code?

ReferenceError (C) Signup and view all the answers

What is the purpose of the try...catch statement in JavaScript?

To handle and provide information about errors (C) Signup and view all the answers

What happens when a run-time error occurs in JavaScript?

The program execution is interrupted and an error message is shown (B) Signup and view all the answers

What is the result of calling 'length' on a number variable in JavaScript?

It throws a TypeError (C) Signup and view all the answers

What is the main purpose of a JavaScript function?

To divide the code into logically independent parts (A) Signup and view all the answers

What is the syntax to declare a function in JavaScript?

function functionName() { code block } (C) Signup and view all the answers

What is the role of parentheses in a function declaration?

They enclose function parameters (D) Signup and view all the answers

Why is it beneficial to test code fragments enclosed in functions?

To test the code independently from the rest of the program (D) Signup and view all the answers

What is the naming convention for a function name?

It must relate to the condition to be done (D) Signup and view all the answers

What is the benefit of using functions in a JavaScript program?

It increases the code's readability (C) Signup and view all the answers

What is the value of the first parameter when the add function is called?

5 (A) Signup and view all the answers

What is the purpose of the getMeanTemp function?

To calculate the mean of a set of temperatures (C) Signup and view all the answers

What is passed to the getMeanTemp function when it is called for the first time?

The day1 variable (C) Signup and view all the answers

What is the result of calling the getMeanTemp function with the day1 variable?

16.733333333333334 (B) Signup and view all the answers

What is the purpose of the for loop in the getMeanTemp function?

To calculate the sum of the temperatures (C) Signup and view all the answers

What is the data type of the temperatures parameter in the getMeanTemp function?

Array (D) Signup and view all the answers

Study Notes

Errors and Exceptions

Errors in programming occur due to misconceptions in problem-solving, improper use of the programming language, or inability to predict user behavior.
Errors can be categorized into syntax errors, semantic errors, and logical errors.
Syntax errors occur when a code is ill-formed, and the JavaScript engine cannot understand it.
Semantic errors occur when a word is not recognizable in the vocabulary of the natural language, or a word is out of context.
Logical errors occur when the intended outcome is not achieved due to incorrect logic.

Error Messages

Uncaught TypeError: Assignment to constant variable occurs when trying to change the value of a constant variable.
Uncaught TypeError: someNumber.length is not a function occurs when trying to get the length of a number.
Uncaught ReferenceError: c is not defined occurs when trying to access a non-existent variable or function.
Uncaught SyntaxError: Unexpected token '{' occurs when there is a typo in the code, such as an extra letter in a keyword.
RangeError occurs when a value is passed to a function outside its acceptable range.

Functions

A function in JavaScript is a separate piece of code intended to perform a specific task.
A function can be called multiple times in different program sections.
A function aims to divide the code into logically independent parts to make a long program easier to write and understand.
A function declaration starts with the function keyword, followed by the function name and parameters, and then the function body.
Functions can take parameters, which are values passed to the function when it is called.

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Description

Learn to identify and fix errors in your JavaScript code. This quiz covers common mistakes, syntax rules, and techniques for debugging. Improve your programming skills and write more efficient code.