Get number of non-empty elements from nested arrays

Question

I have ten arrays with empty value

onTable[0 to 10];

look

["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""]
["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""]
...

I want get length of each array without empty value and without create ten variables for check that.

I have test this solution count empty values in array but i dont want make ten variable. ie: count1, count2,... .

I check too compare two arrays based on length: skip empty values but is not what i want.

If possible, I want this look like

onTable[0].length(exclude(""))

What is the good way for make that?

Answer 1

Use filter with Boolean to filter non-empty elements from sub-array and use length on it.

onTable[0].filter(Boolean).length

As empty string is falsy in JavaScript, it'll be removed from filtered array.

Demo:

 var arr = [ ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""], ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""] ]; var len = arr[1].filter(Boolean).length; document.write(len); 

Answer 2

With a prototype :

 Array.prototype.lengthWihtoutEmptyValues = function () { var initialLength = this.length; var finalLength = initialLength; for (var i = 0; i < initialLength; i++) { if (this[i] == "") { finalLength--; } } return finalLength; } var arrays = [ ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""], ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""] ]; var arrayLength = arrays[0].lengthWihtoutEmptyValues(); $("#arrayLength").html(arrayLength); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <div id="arrayLength"></div> 

Answer 3

You can use filter function for your need: check value to undefined or null etc.

 var arr = [ ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""], ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""] ]; var len = arr[1].filter(function(x){ return x != ""}).length; document.write(len); 

Answer 4

You should avoid "wasting" memory and inducing excessive GC. You can reduce() each sub array to a count of it's non-empty values:

sub.reduce(function(prev, cur) {
  return prev + (!!cur);
}, 0);

In order to process the entire master array, you can map() it to lengths:

 var arr = [ ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""], ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""], ["Just1", "", ""] ]; var lengths = arr.map(function(sub) { return sub.reduce(function(prev, cur) { return prev + (!!cur); }, 0); }); document.write('[' + lengths.join('], [') + ']');