Prevent stop of code execution on undefined value

Question

Often, I write something like this:

if(model.properties.foo.bar){
    // ...
} 

else{
   // ...
}

Currently, I want to fetch a document only if it isn't already cached. To do so, I write an if-statement like above, checking for the title of the current document.

However, if there is no current document because the user just entered my application, this check will fail due to an undefined model.properties. An error is thrown and the else block won't execute.

What is the commonly best practive to write such checks?

`if (model && 'properties' in model && 'foo' in model.properties && 'bar' in model.properties.foo && model.properties.foo.bar)` — adeneo, Jul 22 '14 at 13:35
Sure. I am looking for the cleanest possible way to do this, though, with the least possible effort — user2422960, Jul 22 '14 at 13:36

score 0 · Answer 1 · answered Jul 22 '14 at 13:39

0

if(model.properties != null){

      if (model.properties.foo.bar) {
         // ...
      } else {
         // ...
      }
    // ...
} 

else{
   // ...
}

answered Jul 22 '14 at 13:39

veena

7
1

This will fail if `model` is not defined. – Jongware Jul 25 '14 at 17:10

Prevent stop of code execution on undefined value

1 Answers1