RegExp.prototype.multiline

The multiline accessor property of RegExp instances returns whether or not the m flag is used with this regular expression.

RegExp.prototype.multiline has the value true if the m flag was used; otherwise, false. The m flag indicates that a multiline input string should be treated as multiple lines. For example, if m is used, ^ and $ change from matching at only the start or end of the entire string to the start or end of any line within the string.

Note: To match the start and end of the entire string in m mode, use the buffer boundary assertions A, z, and Z.