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Regular Expressions Note 1: or logic pipe, wildcard, i flag, g flag

One aspect of programming which I often time needed is text or string processing. I often need to reach out to regex (Regular Expression), but honestly most of the time I have no idea what I was typing 😂.

Starting here I'll note some of the things I learned on Regular Expression, so that (hopefully) I will not be as clueless as the usual.

Using pipe

We can match string with or logic using pipe |

const stringToMatch = "I love to eat carrot"
const foodRegex = /carrot|pizza|apple/
const result = foodRegex.test(stringToMatch)

Ignore case sensitivity

When matching using regex the default is we also match the case. To match regex ignoring the case we add i flag to the regex.

const stringToMatch = "Do you like to eat VEGETABLE?"
const vegRegexCaseSensitive = /vegetable/
const vegRegexCaseInsensitive = /vegetable/i
const caseSensitiveResult = vegRegexCaseSensitive.test(stringToMatch)
const caseInsensitiveResult = vegRegexCaseInsensitive.test(stringToMatch)

Wildcard for matching any character

To match any character we can use . wildcard.

const stringToMatch = "The bug in the bag is pretty big"
const regexWithWildcard = /b.g/
const matchResults = stringToMatch.match(regexWithWildcard)

Global flag for matching all occurances

The previous examples only return/match the first occurance of string matched with the regex. To find/match all occurances we can use the g (global) flag on the regex.

const stringToMatch = "The bug in the bag is pretty big"
const regexWithWildcard = /b.g/g
const matchResults = stringToMatch.match(regexWithWildcard)