Read a global variable — practice exercise

What you'll be asked to do

1. 1.Read a global variableexercise · easy · 10 min

   Read a variable declared outside the function from inside it.

   Passes when: #out should show My Site.

2. 2.Keep a variable localexercise · easy · 10 min · practice plan

   Show that a variable declared inside a function does not exist outside.

   Passes when: #out should show undefined.

3. 3.Walk the scope chainexercise · easy · 10 min · practice plan

   Join a value from each of three nested scopes with a dash.

   Passes when: #out should show one-two-three.

4. 4.Shadow an outer variableexercise · easy · 10 min · practice plan

   Declare a variable inside a function with the same name and show the outer one is untouched.

   Passes when: #out should show outer.

5. 5.Pass instead of sharingexercise · medium · 10 min · practice plan

   Pass a value into a function rather than reading a global, and show the result.

   Passes when: #out should show 60.

6. 6.Fix the variable read out of scopebug fix · easy · 8 min

   The variable only exists inside the function.

   Passes when: #out should show 42.

7. 7.Fix the shadowed valuebug fix · easy · 8 min · practice plan

   The inner variable hides the outer one, so the wrong value is returned.

   Passes when: #out should show outer.

8. 8.Fix the broken scope chainbug fix · easy · 8 min · practice plan

   The inner function cannot see a variable declared after it runs.

   Passes when: #out should show one-two-three.

9. 9.Fix the hidden global dependencybug fix · easy · 8 min · practice plan

   The function reads an outside rate, so changing it changes the answer.

   Passes when: #out should show 60.

10. 10.Fix the outer variable overwrittenbug fix · easy · 8 min · practice plan

    The function changes the global instead of using its own copy.

    Passes when: #out should show start.

Between them these tasks cover Global scope, Function scope and Scope chain.

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