[Week 10] The JavaScript Odyssey: History and Essentials

Who created JavaScript?

• James Gosling

• Brendan Eich

• Tim Berners-Lee

• John Resig

Answer explanation

JavaScript was created by Brendan Eich in 1995 while working at Netscape. He developed it in just 10 days, and it has since become one of the core technologies of the web.

In what year was JavaScript created?

• 1992

• 1995

• 1997

• 2000

Answer explanation

JavaScript was created in 1995 by Brendan Eich while working at Netscape. This year marks its official introduction, making it the correct answer among the options provided.

What does ES stand for in ES3, ES5, ES6, etc.?

• Easy Script

• ECMAScript

• Enhanced Script

• Efficient Script

Answer explanation

ES stands for ECMAScript, which is the standard specification for scripting languages like JavaScript. Versions like ES3, ES5, and ES6 refer to different iterations of this standard, making 'ECMAScript' the correct choice.

Which version of ECMAScript introduced arrow functions?

• ES3

• ES5

• ES6

• ES2020

Answer explanation

Arrow functions were introduced in ES6, also known as ECMAScript 2015. They provide a more concise syntax for writing function expressions and lexically bind the 'this' value.

What major feature was introduced in ES2015 (ES6)?

• Strict mode

• Promises

• For-in loops

• Template literals

Answer explanation

Template literals, introduced in ES2015 (ES6), allow for multi-line strings and string interpolation using backticks (`). This feature enhances string manipulation compared to previous methods, making it the correct choice.

Which of the following is a new primitive data type introduced in ES6?

• String

• Symbol

• Object

• Number

Answer explanation

The correct answer is 'Symbol', which is a new primitive data type introduced in ES6. Unlike String, Object, and Number, which were already existing types, Symbol provides a unique identifier that is not visible to the outside world.

What is the purpose of the `let` keyword in JavaScript?

• Declares a global variable

• Declares a block-scoped variable

• Declares a constant variable

• Declares a function

Answer explanation

The `let` keyword in JavaScript is used to declare a block-scoped variable, meaning it is limited to the block in which it is defined. This is different from `var`, which declares a variable globally or within a function.

Which of the following is the correct way to write a single-line comment in JavaScript?

• /* comment */

• // comment

• # comment

What is the correct syntax for declaring a variable?

• var myVariable;

• let myVariable;

• const myVariable;

• All of the above

Answer explanation

The correct syntax for declaring a variable in JavaScript can be done using 'var', 'let', or 'const'. Each keyword serves different purposes, but all are valid for variable declaration, making 'All of the above' the correct choice.

Which of the following is true about the `const` keyword?

• Variables declared with `const` can be reassigned.

• Variables declared with `const` must be initialized.

• `const` variables are globally scoped.

• None of the above.

Answer explanation

The correct choice is that variables declared with `const` must be initialized. Unlike `let` or `var`, `const` requires an initial value at the time of declaration and cannot be reassigned later.