How to detect string which contains only spaces

Question

A string length which contains one space is always equal to 1   alert  My str length      str length     The space is a character  so   str          alert  My str length     str length      My str length  3   How can I make a distinction between an empty string and a string which contains only spaces  How can I detect a string which contain only spaces

User · Answer

if  str trim       console log  string is empty or only contains spaces       Removing the whitespace from a string can be done using String trim    To check if a string is null or undefined  one can check if the string itself is falsey  in which case it is null  undefined  or an empty string  This first check is necessary  as attempting to invoke methods on null or undefined will result in an error  To check if it contains only spaces  one can check if the string is falsey after trimming  which means that it is an empty string at that point  if  str     str trim          str is null  undefined  or contains only spaces    This can be simplified using the optional chaining operator  if  str  trim          str is null  undefined  or contains only spaces    If you are certain that the variable will be a string  only the second check is necessary  if  str trim        console log  quot str is empty or contains only spaces quot

User · Answer

Trim your String value by creating a trim function  var text         if   trim text length    0     console log  Text is empty      else     console log  Text is not empty

User · Answer

Similar to Rory s answer  with ECMA 5 you can now just call str trim   length instead of using a regular expression  If the resulting value is 0 you know you have a string that contains only spaces   if   str trim   length      console log  str is empty         You can read more about trim here

User · Answer

You can Trim your String value by creating a trim function for your Strings   String prototype trim   function          return this replace    s        replace   s              now it will be available for your every String and you can use it as  str trim   length   Result will be 0   You can also use this method to remove the white spaces at the start and end of the String i e     hello    trim       Result will be  hello

User · Answer

The fastest solution would be using the regex prototype function test   and looking for any character that is not a space  tab  or line break  S   if     S  test str          Didn t find something other than a space which means it s empty    In case you have a super long string  it can make a significant difference as it will stop processing as soon as it finds a non-space character

User · Answer

To achieve this you can use a Regular Expression to remove all the whitespace in the string  If the length of the resulting string is 0  then you can be sure the original only contained whitespace  Try this    x000D   x000D  var str           x000D  if   str replace   s g      length    x000D    console log  string only contains whitespace  ie  spaces  tabs or line breaks     x000D    x000D   x000D   x000D

[javascript] How to detect string which contains only spaces?

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