This document summarizes several Ruby methods for checking values - .nil?, .empty?, .blank?, .present?, and .any?. It provides examples of how each method works and what it returns for different data types like strings, arrays, hashes, true/false values, and nil. Key differences are noted, such as .nil? only returning true for nil, .empty?/blank? checking for empty collections, .present? being the inverse of .blank?, and .any? checking if the block ever returns non-false/nil for each element.

1. Difference between
.nil?, .empty?, .bank?,
.present? and .any?
Ruby Syntax Tips
Henry Le

2. .nil?
It is a Ruby method.
It can be used on any objects and will
return true if the object is “null”.

3. .nil? examples
nil.nil? = true ( “Only the object nil
responds true to .nil?” – RailsAPI )
anthing_else.nil? = false

4. .empty?
It is a Ruby method.
Can be used on strings, arrays and
hashes and will return true if their
lengths are zero.
Running .empty? on something that is nil
will throw a NoMethodError.

5. .empty? examples
[].empty? = true
{}.empty? = true
"".empty?= true
" ".empty? = false
nil.empty? => “NoMethodError: undefined
method `empty?' for nil:NilClass"

6. .blank?
It is a Rails method (in ActiveSupport).
Operate on any object as well as work
like .empty? on strings, arrays and
hashes.
It also evaluates true on strings which
are non-empty but contain only
whitespace.

7. .blank? examples
nil.blank? = true
" ".blank? = true
"ntt".blank? = true
[" “].blank? = false
[nil].blank? = false

8. .present?
It is a Rails method (in ActiveSupport).
It is vice versa from .blank?
!obj.blank? == obj.present?

9. .present? examples
nil.present? = false
false.present? = false
true.present? = true
[].present? = false
[“"].present? = true
[nil].present?

10. .any?
Pass each elements of the collection to
the given block the returns true if the
block ever returns a value other than
false or nil.

11. .any? examples
[nil, false].any? = false
We can customise the condition to return
true:
[nil, false].any? { |w| w == false } = true
%w{ant bear cat}.any? { |word|
word.length >= 3 } = true

12. .present? vs .any?
[nil, false].present? = true
[nil, false].any? = false

13. Conclusion