Detailed explanation of the use of u modifier in regular expressions (with code)

This time I will bring you Regular expressiondetailed explanation of the use of u modifier (with code), what are the precautions for using the u modifier of regular expression, the following are Let’s take a look at practical cases.

Regular expression u modifier:

This modifier identifies the ability to correctly handle Unicode characters larger than \uFFFF.
In other words, four-byte UTF-16 encoding will be processed correctly.
This modifier is new in ES2015. For more new features of regular expressions, please refer to the chapter "New Features of Regular Expressions in ES2015".
For more regular expression tutorials, please refer to the regular expression tutorial section.

Code example:

console.log(/^\uD842/u.test("\uD842\uDFB7"))

Output false, because "\uD842\uDFB7" is a four-byte UTF-16 encoding, representing a character, so if the regular expression has u modifier, then you will be able to identify it.

console.log(/^\uD842/.test("\uD842\uDFB7"))

Output true; without adding the u modifier, the four-byte UTF-16 encoding cannot be recognized as one character, so a match can be generated.

/^.$/.test("\uD842\uDFB7")//false
/^.$/u.test("\uD842\uDFB7")//true

For the usage of metacharactersdot (.), please refer to the chapter of regular expressions.dot metacharacter.

/^.$/.test("\uD842\uDFB7")//false
/^.$/u.test("\uD842\uDFB7")//true

After adding the u modifier, dot metacharacters can match Unicode characters with code points greater than 0xFFFF.

/ \u{61} /.test("a")//false
/ \u{61} / u.test("a")//true

Using the u modifier, the regular expression can recognize the Unicode characters represented by braces {}, otherwise it cannot be recognized. {61} will also be interpreted as a quantifier, indicating 61 u character.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

Recommended reading:

Regular Expressions Detailed explanation of the use of \W metacharacters (with code)

Regular Expressions Detailed explanation of the use of . metacharacter (with code)

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