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I'm parsing some fields out of a string, and I'm having a bit of difficulty getting the extraction correct.

My string can be formatted as such:

const myString = 'field1=field1_value;field2=field2_value'

Or

const myString = 'field1=field1_value'

In this example below, I'm trying to extract field1 and field2 out of the first string.

I've done something like:

const field1 = myString.match(/field1=(.*)(;)?/);
const field2 = myString.match(/field2=(.*)(;)?/);

The problem with this, is that for field1, it will match all the way from the beginning until the end of the string, including all the other fields. If I make the delimiter a mandatory match, then field2 doesn't match anything, as the last field in the string won't have any delimiters. I want this extraction to happen in a way that if a delimiter is present, it should only match up to that and since the last field doesn't have it, or if it is a single field without the delimiter, it should still extract it.

How can I form my regex to do this type of extraction?

Wiktor Stribiżew
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azdiiv
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3 Answers3

1

For a simple pattern like this you don't actually need regex. You could just do something like this: myString.split(';').map(field => field.split('=')[1]) to get an array of values.

Tom Nijs
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Your first group should be non-greedy, matching as few characters as possible before the next group. The same would work for subsequent fields as long as they end with a semicolon. 

const field1 = myString.match(/field1=(.*?)(;)/);
const field2 = myString.match(/field2=(.*)/);

However, if your final field doesn't end in a semicolon, you'd need a different regex for it.

Edit: Disregard this answer. Anubjava gave you a much better solution in the comments:

const field1 = myString.match(/\bfield1=([^;]+)/);
thingEvery
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You may try

(\w+)=([^;]+)

See a demo on regex101.com.

Jan
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