JSLint and JSHint (before version 1.0.0) will throw the "Spaces are hard to count. Use {a}" error when they encounter a regular expression literal containing multiple consecutive space characters. In the following example we define a regular expression that will match the string "three spaces" (there are three spaces between the two words):
This error is raised to highlight a potentially confusing piece of code. Your script will run without error if you do not change it, but it could be confusing to other developers, especially at first glance.
Anyone who wants to understand exactly what the regular expression should match will have to stop and count the number of spaces. This is unnecessary, since there is an alternative syntax that makes it much clearer. To fix this error, simply use the repetition operator:
Alternatively, you could modify your code to use the RegExp constructor rather than a regular expression literal, since JSLint and JSHint will only raise this error inside a literal:
This article was written by James Allardice, an enthusiastic young JavaScript developer at Global Personals (we're looking for front-end developers so please apply). He is passionate about writing clean, maintainable JavaScript and uses JSHint every day to help achieve this.
You can follow him on Twitter, fork him on GitHub and find him on Google+.