JavaScript lessons: learn from scratch

Short lessons: the first line, then a condition, a loop and a function. Written by Nibras Code.

Questions and answers

How do I start JavaScript? console.logWrite one sentence with console.log on your first HTML page.
JavaScript if, for and functionsWrite a condition, a loop and your own function.
JavaScript arrays: push and lengthKeep several values in one list, add an item at the end and read the count.
JavaScript: walk an array with a for loopRead the items, find the sum and the largest, pick the evens and walk the array backwards.
What happens when a button is clicked in JavaScript?A click event, changing text and a counter.
JavaScript: read text from an inputprompt, HTML input.value and turning text into a number. Cancel returns null.
A JavaScript error: what does undefined mean?A variable with no value, a missing index and the difference from null.