How to check if a multidimensional array item is set in JS?

javascript arrays multidimensional-array isset
Colargol picture Colargol · Jun 2, 2013 · Viewed 11.6k times · Source

How to check if a multidimensional array item is set in JS?

w[1][2] = new Array;
w[1][2][1] = new Array;
w[1][2][1][1] = 10; w[1][2][1][2] = 20; w[1][2][1][4] = 30;

How to check if w[1][2][1][3] is set?

Solution with if (typeof w[1][2][1][3] != 'undefined') doesn't work.

I don't want to use an Object instead of Array.

Answer

Patrick Evans picture Patrick Evans · Jun 2, 2013

You are not checking the previous array elements existence before checking its children as the children elements cant exist if the parent doesnt 

if( 
    typeof(w) != 'undefined' &&
    typeof(w[1]) != 'undefined' &&
    typeof(w[1][2]) != 'undefined' &&
    typeof(w[1][2][1]) != 'undefined' &&
    typeof(w[1][2][1][3]) != 'undefined' &&
  ) {
    //do your code here if it exists  
  } else {
    //One of the array elements does not exist
  }

The if will run the code in the else clause if it sees any of the previous elements not existing. It stops checking the others if any of the preceding checks returns false.

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