Count of “Defined” Array Elements

by

In recent browser, you can use filter

var size = arr.filter(function(value) { return value !== undefined }).length;

console.log(size);

Another method, if the browser supports indexOf for arrays:

var size = arr.slice(0).sort().indexOf(undefined);

If for absurd you have one-digit-only elements in the array, you could use that dirty trick:

console.log(arr.join("").length);

There are several methods you can use, but at the end we have to see if it’s really worthy doing these instead of a loop.

More Related Contents:

  1. Detecting an undefined object property
  2. What is the difference between null and undefined in JavaScript?
  3. Why is null an object and what’s the difference between null and undefined?
  4. How can I unset a JavaScript variable?
  5. How to check a not-defined variable in JavaScript
  6. variable === undefined vs. typeof variable === “undefined”
  7. How to check for an undefined or null variable in JavaScript?
  8. JavaScript checking for null vs. undefined and difference between == and ===
  9. Why does this JavaScript code print “undefined” on the console?
  10. forEach on array of undefined created by Array constructor
  11. JavaScript “cannot read property “bar” of undefined [duplicate]
  12. Why is there a `null` value in JavaScript?
  13. How dangerous is it in JavaScript, really, to assume undefined is not overwritten?
  14. node.js displays “undefined” on the console
  15. this is undefined inside arrow function
  16. What reason is there to use null instead of undefined in JavaScript?
  17. JavaScript String concatenation behavior with null or undefined values
  18. When is null or undefined used in JavaScript? [duplicate]
  19. Javascript – removing undefined fields from an object [duplicate]
  20. How to compare variables to undefined, if I don’t know whether they exist? [duplicate]
  21. Undefined return value from the function call Javascritpt
  22. console.log(myFunction()) returns undefined
  23. JS checking deep object property existence [duplicate]
  24. What’s the difference between empty items in a JavaScript array and undefined? [duplicate]
  25. Is it better to return `undefined` or `null` from a javascript function? [closed]
  26. Can I set variables to undefined or pass undefined as an argument?
  27. Should JSON include null values [closed]
  28. Why is my JavaScript hoisted local variable returning undefined but the hoisted global variable is returning blank? [duplicate]
  29. Set a variable if undefined in JavaScript
  30. Test if something is not undefined in JavaScript

Leave a Comment