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JavaScript, Regular-expression, Replace

JavaScript, Regular-expression, Replace

I am trying to use a regular expression to correct an HL7 msg.
Using 'replace' to search the inbound text message and find segments that are not correctly terminated w/carriage returns.

Example: // this works

var msg = "MSH|...|...|\rGT1|...|...|GT1|...|...|\r";
msg = msg.replace(/\|GT1\|/g, "|\rGT1|");

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// This leaves me with:

MSH|...|...|\r
GT1|...|...|\r
GT1|...|...|\r

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// but, I don't always know that the 2nd instance of 'GT1' will be proceeded w/a '|' (pipe) character.
How do I search for any character in the 1st (search) argument and get it into the 2nd (replace) argument ?

var msg = "MSH|...|...|\rGT1|...|...|GT1|...|...|\r";
msg = msg.replace(/.GT1\|/g, ".\rGT1|");
// What goes here  ^ and Here ^

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I need to avoid adding a double \r\r !

Thank you.

zc2

Did you try

msg.replace(/[^\r]GT1\|/g, "|\rGT1|")

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sidwelle

ASKER

No, wouldn't that replace any line that begins with "\rGT1|" w/ "|\rGT1|" ?
I don't know what 'GT1' will be prefixed with, I just don't it be acted on if is prefixed with \r.
I need strings of '\rGT1|' to be excluded from the replace.

Thank you.

ASKER CERTIFIED SOLUTION

zc2

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sidwelle

ASKER

That line works, not sure what '$1' does. I suppose it replaces the first token, can't seem to find any documentation on it ?

Thanks

zc2

Here is some info:
https://docs.microsoft.com/en-us/dotnet/standard/base-types/substitutions-in-regular-expressions

sidwelle

ASKER

Thanks for the help, that's what I needed to see !

Sorry I can't provide a more complex example, all the msgs are full of PHI.

Thanks

zc2

You are welcome!