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up vote 16 down vote favorite
3

I am working with titanium ,

my code looks like as ,

var currentData = new Array();

if(currentData[index]!==""||currentData[index]!==null||currentData[index]!=='null')
{
    Ti.API.info("is exists  " + currentData[index]);
    return true;
}
else
{   
    return false;
}

I am passing index to array currentData,

For non existing element , i am still not able to detect it using above code

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1  
Your logic is wrong. You need conjunctions (&&) between the individual conditions. –  Jan Kuča Oct 28 '12 at 9:59

4 Answers 4

up vote 29 down vote accepted

Use typeof arrayName[index] == 'undefined'

i.e.

if(typeof arrayName[index] == 'undefined') {
    // does not exist
}
else {
    // does exist
}
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2  
+1, nice. You can also use if(arrayName[index] === 'undefined') as a shortcut –  AnchovyLegend Oct 8 '13 at 0:08
10  
@AnchovyLegend no, you cannot! But you can use if(arrayName[index] === undefined). –  Denis V Nov 29 '13 at 15:01
2  
this fails, if the item is there, but it's value is undefined; use this answer instead -> stackoverflow.com/questions/1098040/… –  Matus May 17 at 21:25
    
as @Matus said, there is more explanation here, you should be aware on. –  mansoulx Aug 8 at 8:47
up vote 15 down vote 
var myArray= ["Banana", "Orange", "Apple", "Mango"];

if(myArray.indexOf(searchTerm)==-1)
  alert("element doesn't exist");
else
  alert("element found");
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up vote 0 down vote

I had to wrap techfoobar's answer in a try..catch block, like so:

try {
  if(typeof arrayName[index] == 'undefined') {
    // does not exist
  }
  else {
  // does exist
  }
} 
catch (error){ /* ignore */ }

...that's how it worked in chrome, anyway (otherwise, the code stopped with an error).

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up vote 0 down vote

If you use underscore.js then these type of null and undefined check are hidden by the library.

So your code will look like this -

var currentData = new Array();

if (_.isEmpty(currentData)) return false;

Ti.API.info("is exists  " + currentData[index]);

return true;

It looks much more readable now.

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