Removing undefined values 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.
You can use lodash compact method, which removes null, undefined and ''
_.compact(data)