| |
| function test_in() |
| { |
| |
| // Arrays |
| var trees = new Array("redwood", "bay", "cedar", "oak", "maple"); |
| 0 in trees // returns true |
| 3 in trees // returns true |
| 6 in trees // returns false |
| "bay" in trees // returns false (you must specify the index number, |
| // not the value at that index) |
| "length" in trees // returns true (length is an Array property) |
| |
| // Predefined objects |
| "PI" in Math // returns true |
| |
| // Custom objects |
| var mycar = {make: "Honda", model: "Accord", year: 1998}; |
| "make" in mycar // returns true |
| "model" in mycar // returns true |
| |
| |
| |
| var color1 = new String("green"); |
| "length" in color1 // returns true |
| var color2 = "coral"; |
| "length" in color2 // generates an error (color is not a String object) |
| |
| |
| var mycar = {make: "Honda", model: "Accord", year: 1998}; |
| delete mycar.make; |
| "make" in mycar; // returns false |
| |
| var trees = new Array("redwood", "bay", "cedar", "oak", "maple"); |
| delete trees[3]; |
| 3 in trees; // returns false |
| |
| |
| var mycar = {make: "Honda", model: "Accord", year: 1998}; |
| mycar.make = undefined; |
| "make" in mycar; // returns true |
| |
| |
| var trees = new Array("redwood", "bay", "cedar", "oak", "maple"); |
| trees[3] = undefined; |
| 3 in trees; // returns true |
| |
| } |