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up vote 25 down vote favorite
4

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

5 Answers 5

up vote 48 down vote accepted

Use typeof arrayName[index] === 'undefined'

i.e.

if(typeof arrayName[index] === 'undefined') {
    // does not exist
}
else {
    // does exist
}
share|improve this answer
3  
+1, nice. You can also use if(arrayName[index] === 'undefined') as a shortcut –  AnchovyLegend Oct 8 '13 at 0:08
12  
@AnchovyLegend no, you cannot! But you can use if(arrayName[index] === undefined). –  Denis V Nov 29 '13 at 15:01
4  
this fails, if the item is there, but it's value is undefined; use this answer instead -> stackoverflow.com/questions/1098040/… –  Matus May 17 '14 at 21:25
    
as @Matus said, there is more explanation here, you should be aware on. –  S.Thiongane Aug 8 '14 at 8:47
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 21 down vote 
var myArray= ["Banana", "Orange", "Apple", "Mango"];

if(myArray.indexOf(searchTerm)==-1)
  alert("element doesn't exist");
else
  alert("element found");
share|improve this answer
1  
Unfortunately, this one doesn't work in IE 7 and below. –  darksoulsong Oct 7 '14 at 15:21
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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Even if your answer is right, I would just think twice for this. Your code would become underscore.js dependent only for checking an empty value. Just do a simple wrapper function isset(v) { return (typeof v !== 'undefined'); } –  Heroselohim Nov 26 '14 at 14:55
up vote 0 down vote

If elements of array are also simple objects or arrays, you can use some function:

// search object
var element = { item:'book', title:'javasrcipt'};

[{ item:'handbook', title:'c++'}, { item:'book', title:'javasrcipt'}].some(function(el){
    if( el.item === element.item && el.title === element.title ){
        return true; 
     } 
});

[['handbook', 'c++'], ['book', 'javasrcipt']].some(function(el){
    if(el[0] == element.item && el[1] == element.title){
        return true;
    }
});
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