RegExp javascript replace all not work

Question

i confused with this code

<!DOCTYPE html>
<html>

    <body>
        <p>Click the button to replace "Microsoft" with "W3Schools" in the paragraph
            below:</p>
        <p id="demo">Microsoft Visit Microsoft! Microsoft visit visit microsoft Visit Visit
            Visit Visit</p>
        <button onclick="myFunction()">Try it</button>
        <script>
            function myFunction() {
                document.getElementById("demo").innerHTML = document.getElementById("demo").innerHTML.replace(/ Visit |Microsoft/gi, ' test ');
            }
        </script>
    </body>

</html>

when click on button some words didn't change,if click again will change

after first click

test test test ! test test visit test test Visit test Visit

after second click

test test test ! test test test test test test test test

why some words didn't change in first time? sincerely

@Салман yes i developing a toolbar and inject some thing to pages — MD66
– MD66, Commented Jan 27, 2013 at 17:34

VisioN · Accepted Answer · 2013-01-27 16:39:19Z

2

This happens because in your #demo contents two not replaced Visit words do not have space after it (the first has new line, the second has line end).

In order to fix it, instead you may use \b as word boundary: /\bVisit\b|Microsoft/gi.

DEMO: http://jsfiddle.net/dyz5w/

answered Jan 27, 2013 at 16:39

VisioN

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1 Comment

Matthijs Wessels Over a year ago

Even though your solution works, the problem is not caused by the new line and the line end, but rather by what Justin Morgan mentioned in his answer. If the line end would be a problem, then how does the second click replace that Visit? If I use the OP's original regex in your jsfiddle, the second click doesn't replace the last two Visits. So I think the OP's html probably has some spaces around the visits before the new and end line.

Justin Morgan · Accepted Answer · 2013-01-27 16:46:23Z

1

It's happening because of the spaces around Visit in your regex:

 / Visit /

That requires a space on either side of the word "visit". Regex matches don't overlap, so if you have a string like

  Visit Visit Visit Visit

....then both of the spaces between each instance of "visit" can only belong to a single match. So your regex matches will look like this (using { to show where a match begins and } to show where it ends):

 { Visit }Visit{ Visit }Visit

Try it with two spaces between the "Visit"s. You'll see that it gets them all.

Edit: VisioN beat me to it; his suggestion of using \b is perfect if you want to match only the words.

answered Jan 27, 2013 at 16:46

Justin Morgan

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1 Comment

MD66 Over a year ago

i want to search for words and \b is good choice for me thanks

inhan · Accepted Answer · 2013-01-27 16:47:21Z

0

/ Visit |Microsoft/gi simply means

find " Visit " (with spaces around)
| (or)
find "Microsoft"
the g flag - find all the matches
the i flag - make a case insensitive search

answered Jan 27, 2013 at 16:47

inhan

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