delete undefined from array javascript code example

Example 1: remove undefined from array javascript

var data = [42, 21, undefined, 50, 40, undefined, 9];

data = data.filter(function( element ) {
   return element !== undefined;
});

Example 2: remove null from array javascript

let array = [0, 1, null, 2, 3];

function removeNull(array) {
return array.filter(x => x !== null)
};

Example 3: remove undefined from array

//? to use Array.prototype.filter here might be obvious. 
//So to remove only undefined values we could call

var data = [42, 21, undefined, 50, 40, undefined, 9];

data = data.filter(function( element ) {
   return element !== undefined;
});

//If we want to filter out all the falsy values (such as 0 or null),
//we can use return !!element; instead. But we can do it slighty more elegant,
//by just passing the Boolean constructor function,
//respectively the Number constructor function to .filter:

data = data.filter( Number );

//That would do the job in this instance,
//to generally remove any falsy value,
//we would call
data = data.filter( Boolean );
//Since the Boolean() constructor returns true on truthy values
//and false on any falsy value, this is a very neat option.

Example 4: remove empty values from array javascript

var array = [0, 1, null, 2, "", 3, undefined, 3,,,,,, 4,, 4,, 5,, 6,,,,];

var filtered = array.filter(function (el) {
  return el != null;
});

console.log(filtered);