javascript regex - why is my captured string wrong?

Question

I need to replace a occurrences within a string with variable occurrences and then reconstruct the string. I figured some regex magic with javascript and it should be a snap. However, after much fussing and banging of my head I reach out to my stack overflow brothers and sisters for their keen eye.

I am trying to remove [[XYZ]] as in the following code:

<!DOCTYPE html>
<html>
<body>

<p>Click the button to replace and switch:</p>

<p id="demo">{
  "[[XYZ]]-ENGINES": "L300",
  "[[XYZ]]-INTERIOR": "BURGCOMDDD",
  "[[XYZ]]-BASEBOAT": "PUTT"
}
</p>

<button onclick="myFunction()">Try it</button>

<script>

function replaceAll(string, find, replace) {
    return string.replace(new RegExp(find, 'g'), replace);
}

function myFunction() {

    var str = document.getElementById("demo").innerHTML; 
    var replaceString = "\"[[XYZ]]?-*(.+)\": \"([A-Z0-9]+)\"?,*"
    var replacementString = '$1/$2 = true,';

        newstr = replaceAll(str, replaceString, replacementString)
        alert(newstr)

}

</script>

</body>
</html>

BUT, when I run it returns:

{
    [XYZ]]-ENGINES/L300 = true,
    [XYZ]]-INTERIOR/BURGCOMDDD = true,
    [XYZ]]-BASEBOAT/PUTT = true,
}

when it should be:

{
    ENGINES/L300 = true,
    INTERIOR/BURGCOMDDD = true,
    BASEBOAT/PUTT = true,
}

Wh?

Is the [[XYZ]]- are a fixed prefix? If it is, you can do it in a very simpler way. — Dinei
– Dinei, Commented May 25, 2015 at 21:12
Yes it is a fixed prefix. By the way, none of the other answers have worked. — jimijon
– jimijon, Commented May 25, 2015 at 23:20

Oriol · Accepted Answer · 2015-05-25 21:17:28Z

1

You must escape [ with \. But wait, since you use a string instead of a regex literal, you must escape \ with another \:

'"[[XYZ]]-ENGINES": "L300"'.replace(
    new RegExp("\"\\[\\[XYZ]]?-*(.+)\": \"([A-Z0-9]+)\"?,*", 'g'),
    '$1/$2 = true,'
);

answered May 25, 2015 at 21:17

Oriol

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1 Comment

jimijon Over a year ago

This worked!! It was the double \\ that was the secret ingredient. thanks.

Streetlamp · Accepted Answer · 2015-05-25 21:13:14Z

0

Try using

function myFunction() {
    var str = document.getElementById("demo").innerHTML; 
    var newstr = str.replace(/\[\[XYZ\]\]-/g, "");
    alert(newstr);
}

You will need to escape special characters such as [ or ]

I removed your function, I hope that's okay.

answered May 25, 2015 at 21:13

Streetlamp

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Comments

Code Different · Accepted Answer · 2015-05-25 21:14:43Z

0

You need to escape [ and ]:

var replaceString = "\"\[\[XYZ\]\]?-*(.+)\": \"([A-Z0-9]+)\"?,*"

answered May 25, 2015 at 21:14

Code Different

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