Report a number's type — practice exercise

What you'll be asked to do

1. 1.Report a number's typeexercise · easy · 10 min

   Use typeof to show the type of the value 7.

   Passes when: #out should show number.

2. 2.Report a string's typeexercise · easy · 10 min · practice plan

   Use typeof to show the type of "hello".

   Passes when: #out should show string.

3. 3.Convert a string to a numberexercise · easy · 10 min · practice plan

   Turn the string "25" into a number and add 5 to it.

   Passes when: #out should show 30.

4. 4.Convert a number to a stringexercise · easy · 10 min · practice plan

   Turn 99 into a string and show its length.

   Passes when: #out should show 2.

5. 5.Check for an arrayexercise · medium · 10 min · practice plan

   Show whether [1,2,3] is an array, as true or false.

   Passes when: #out should show true.

6. 6.Fix the string additionbug fix · easy · 8 min

   Adding two numeric strings joins them instead of summing them.

   Passes when: #out should show 8, not 53.

7. 7.Fix the typeof check on an arraybug fix · easy · 8 min · practice plan

   This reports "object" instead of confirming an array.

   Passes when: #out should show true.

8. 8.Fix the wrong equalitybug fix · easy · 8 min · practice plan

   Loose equality makes this comparison true when it should be false.

   Passes when: #out should show false.

9. 9.Fix the undefined property readbug fix · easy · 8 min · practice plan

   Reading a missing property shows undefined instead of the count.

   Passes when: #out should show 3.

10. 10.Fix the number that became textbug fix · easy · 8 min · practice plan

    The total is joined as text because one value is a string.

    Passes when: #out should show 15, not 105.

Between them these tasks cover Primitive types, typeof and Type conversion.

Looking for a different chapter? See every practice set, or switch to the interview theory questions.