30 Questions
What is a main cause of errors in the operation of programs?
Inability to predict user behavior and improper use of the programming language
What is the 'grammar' of a programming language?
The set of rules that defines the structure of the instructions
What type of error is 'pth' in the example?
Semantic Error
Why is the direction 'left' an error in the example?
It is a logical error
What is the original intended direction in the example?
Right
Why is the error 'left' not easily detectable by the compiler?
It is a logical error
What type of error occurs when a code is ill-formed or has typos?
SyntaxError
What happens when a programmer tries to access a function or variable that does not exist?
A ReferenceError occurs
What type of error occurs when a specific value is not of the expected type?
TypeError
What happens when a constant value is assigned a new value?
A TypeError occurs
What error occurs when trying to access the length of a variable that is not a string?
TypeError
What happens when there is an unmatching parenthesis or bracket in the code?
A SyntaxError occurs
What type of error occurs when a value is passed to a function outside its acceptable range?
RangeError
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
What type of error is caused by the typo 'conole' in the code?
ReferenceError
What is the purpose of the try...catch statement in JavaScript?
To handle and provide information about errors
What happens when a run-time error occurs in JavaScript?
The program execution is interrupted and an error message is shown
What is the result of calling 'length' on a number variable in JavaScript?
It throws a TypeError
What is the main purpose of a JavaScript function?
To divide the code into logically independent parts
What is the syntax to declare a function in JavaScript?
function functionName() { code block }
What is the role of parentheses in a function declaration?
They enclose function parameters
Why is it beneficial to test code fragments enclosed in functions?
To test the code independently from the rest of the program
What is the naming convention for a function name?
It must relate to the condition to be done
What is the benefit of using functions in a JavaScript program?
It increases the code's readability
What is the value of the first parameter when the add function is called?
5
What is the purpose of the getMeanTemp function?
To calculate the mean of a set of temperatures
What is passed to the getMeanTemp function when it is called for the first time?
The day1 variable
What is the result of calling the getMeanTemp function with the day1 variable?
16.733333333333334
What is the purpose of the for loop in the getMeanTemp function?
To calculate the sum of the temperatures
What is the data type of the temperatures parameter in the getMeanTemp function?
Array
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.
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.
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