JavaScript Keywords Reference

False: Keywords and variable names are case sensitive. For example, Var and var would be considered different identifiers in most programming languages, including JavaScript.

In JavaScript, variable names are case-sensitive and must start with a letter, underscore (_), or dollar sign ($). They can't begin with a number. Subsequent characters can be letters, digits, underscores, or dollar signs. Reserved keywords like let and const can't be used as names. Following these rules helps keep your code clear and error-free.

'camelCase' is a way of writing compound words or phrases where each word, except the first, starts with a capital letter, and no spaces or underscores are used. For example, myVariableName and firstName. It's commonly used in programming for naming variables and functions because it's easier to read and understand.

JavaScript has several data types, including primitive types like strings, numbers, booleans, undefined, null, symbols, and BigInt. Additionally, it includes complex types like objects, arrays, functions, dates, and regular expressions. Each of these types serves different purposes, allowing JavaScript to handle a wide range of applications efficiently.

A boolean data type represents a value that can be either true or false. It's often used in programming to make decisions and control the flow of logic, such as in conditional statements and loops. Think of it as a simple on/off switch for various checks and comparisons in your code.

If you forget to put quotes around a string when initializing a variable to a string value in JavaScript, such as var lastName = Jones;, JavaScript will interpret Jones as an undefined variable or identifier rather than a string. This will result in a ReferenceError because JavaScript will try to find a variable named Jones which hasn't been declared.

n JavaScript, a statement is typically ended with a semicolon (;). While JavaScript can often infer where statements end, explicitly using semicolons helps ensure your code runs as intended and avoids potential errors.

If you declare a variable in JavaScript but do not initialize it, the variable will store the value undefined. This indicates that the variable has been declared but has not yet been assigned a value.

const firstTestScore = 98;
const secondTestScore = "88";
const sum = firstTestScore + secondTestScore;
console.log(sum);
console.log(typeof sum);

When you run the program, you'll see "9888" and "string" in the console. This happens because the number 98 is added to the string "88", and JavaScript treats them both as strings and sticks them together, making "9888". The console.log(sum); shows this result, and console.log(typeof sum); tells you that sum is a string. This is an example of how JavaScript combines different types of data.

const total = 99;
console.log("total");
console.log(total);

When you run the program, you'll see "total" and "99" in the console. The console.log("total"); line prints the word "total" as a string. Then, console.log(total); prints the value of the total variable, which is 99. So, you first see the word "total" and then the number 99 on the next line.

const score1 = 75;
const score2 = "75";

The difference between score1 and score2 is in their types. score1 is a number (75), used for math operations and comparisons. On the other hand, score2 is a string ("75"), which is treated as text. Even though they look the same, score1 and score2 behave differently because one is a number and the other is a string

const score = 0;
score = prompt("Enter a score");

This code will make the program crash because score is declared with const, which means it can't be changed once it's set. When the program tries to change score with the value from prompt("Enter a score");, it throws an error since const variables can't be reassigned. To fix this, you can use let instead of const, which allows score to be changed.