regex optional whitespace characters

JavaScript
// Add a \s? if a space can be allowed.
// \s stands for white space
// ? says the preceding character may occur once or not occur.
// If more than one spaces are allowed and is optional, use \s*.
// * says preceding character can occur zero or more times.

'#<a href\s?="(.*?)" title\s?="(.*?)"><img alt\s?="(.*?)" src\s?="(.*?)"[\s*]width\s?="150"[\s*]height\s?="(.*?)"></a>#'
Source

Also in JavaScript: