Arrays have a property called length, and it's pretty much exactly as it sounds, it's the length of the array.

var array = [1 , 2, 3];

// Result: l = 3
var l = array.length;

{% exercise %} Define the variable a to be the number value of the length of the array {% initial %} var array = [1, 1, 2, 3, 5, 8]; var l = array.length; var a = {% solution %} var array = [1, 1, 2, 3, 5, 8]; var l = array.length; var a = 6; {% validation %} assert (a === 6) {% endexercise %}