Why do empty JavaScript arrays evaluate to true in conditional structures?

by

From http://www.sitepoint.com/javascript-truthy-falsy/

The following values are always falsy:

  • false
  • 0 (zero)
  • “” (empty string)
  • null
  • undefined
  • NaN (a special Number value meaning Not-a-Number!)

All other values are truthy, including "0" (zero in quotes), "false" (false in quotes), empty functions, empty arrays ([]), and empty objects ({}).

Regarding why this is so, I suspect it’s because JavaScript arrays are just a particular type of object. Treating arrays specially would require extra overhead to test Array.isArray(). Also, it would probably be confusing if true arrays behaved differently from other array-like objects in this context, while making all array-like objects behave the same would be even more expensive.

More Related Contents:

  1. How to remove all duplicates from an array of objects?
  2. How to get the difference between two arrays of objects in JavaScript
  3. Converting a JS object to an array using jQuery
  4. Remove array element based on object property
  5. Why can I add named properties to an array as if it were an object?
  6. Most efficient way to convert an HTMLCollection to an Array
  7. Sum JavaScript object propertyA values with the same object propertyB in an array of objects
  8. Merge multiple objects inside the same array into one object [duplicate]
  9. How can I get the index of an object by its property in JavaScript?
  10. Why Array.indexOf doesn’t find identical looking objects
  11. How to get objects value if its name contains dots?
  12. Create an empty object in JavaScript with {} or new Object()?
  13. How do I remove an object from an array with JavaScript? [duplicate]
  14. JavaScript – get array element fulfilling a condition
  15. Perform .join on value in array of objects
  16. Create a reset of javascript Array prototype when Array.prototype has been modified?
  17. break array of objects into separate arrays based on a property
  18. Getting index of an array’s element based on its properties
  19. Deep comparison of objects/arrays [duplicate]
  20. Group by, and sum, and generate an object for each array in JavaScript
  21. Uncaught TypeError: Object.values is not a function JavaScript
  22. JavaScript: Remove duplicates of objects sharing same property value
  23. Filtering array of objects by searching nested object properties
  24. traversing through JSON string to inner levels using recursive function
  25. Javascript pushing objects into array changes entire array
  26. Combining two arrays to form a javascript object
  27. How to group an array of objects based on multiple keys in Javascript?
  28. Best way to flatten JS object (keys and values) to a single depth array
  29. Converting Array of Objects into Array of Arrays
  30. How can I remove an element from a list, with lodash?

Leave a Comment