Level 1
Variables
Predict Output
Predict the output
Read the JavaScript code below carefully and select what will be logged to the console.
Hint:
Remember that .filter() always returns a new array with matching elements.
Explanation after each answer
Correct!
You correctly predicted how this JavaScript operates.
Topic Practice
Quick JavaScript Notes
.filter()
Returns a new array of elements where callback returned truthy. Never modifies original.
.map()
Transforms every item into a new array of exact same length.
=== vs ==
Prefer === when you do not intentionally want coercion. == follows coercion rules before comparison.
0-based Indexes
First item is at [0]. Last item is at [arr.length - 1].
Review Recent Questions
Revisit previously answered or missed questions to solidify your intuition.