How to use regex in JavaScript to find out if a string starts with a period?

Question

I am new to regular expressions.

The following code works as expected, first prints “true” and then “false”, the backslash before the period that eludes it:

var pattern = new RegExp(/\./);
document.write(pattern.test("."));
document.write(pattern.test("a"));

But why is the following print "false":

var pattern = new RegExp(/\b\./);
document.write(pattern.test("."));

The period, after all, is at the beginning of the line.

+3

zjmiller May 14, '11 at 1:51

2 answers

This does not work, because in order to break a word, you must first have a word.

Using \b, this will work:

var pattern = new RegExp(/a\b\./);
document.write(pattern.test("a."));

, , , , .

".".charAt(0) === "."

+1

manojlds · Accepted Answer · 2011-05-14T01:53:57+0000

Do you want to try using ^-

/^\./

If you

/\b\./

he matches .inHello. How are you.