JavaScript Quirks and Coercion

Who created JavaScript in 1995?

• Guido van Rossum
• James Gosling
• Tim Berners-Lee
• Brendan Eich

Which operator is strict equality?

• =
• ===
• ==
• !=

The expression 5 == "5" returns true in JavaScript.

• True
• False

Converting values from one type to another before comparing is called type ____.

• binding
• coercion
• hoisting
• casting

What does NaN === NaN return?

• undefined
• false
• true
• NaN

What does the expression 1 + "2" produce?

• "12"
• 3
• -1
• "3"

What does typeof null return?

• "object"
• "null"
• "NaN"
• "undefined"

Moving declarations to the top of their scope is called ____.

• sorting
• coercion
• hoisting
• casting

let and const were introduced in which version?

• ES6 (2015)
• ES2020
• ES3 (1999)
• ES5 (2009)

Variables declared with var are hoisted and given the value null.

• True
• False

let and const exist in the "temporal ____ zone" before declaration.

• dead
• null
• empty
• void

What does 0.1 + 0.2 produce in JavaScript?

• 0.3
• 0.29999999
• 0.30000000000000004
• 0.30000001

Why does default sort() give odd number order?

• Random order
• Sorts as text
• Sorts descending
• Ignores duplicates

null is loosely equal to undefined but not to zero.

• True
• False

Which function checks for NaN?

• typeof()
• isFinite()
• parseInt()
• Number.isNaN()