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Assertion ↔ RegExp Syntax to define boundary of lines/words

^

RegExp Assertion to negate Character Class or only match start of line

$​

RegExp Assertion to match n expression at end of line

|​

RegExp Assertion OR operator for alternative characters/expressions

\b​

RegExp Assertion to match only at boundary of word (beginning or end of word)

\B​

inverted RegExp Assertion to match only at not boundary of word (beginning or end of word)

n(?=abc)​

Positive Lookahead to match n only if abc exists ahead

n(?!abc)​

Negative Lookahead to match n only if abc not exist ahead

(?<=abc)n​

Positive Lookbehind Assertion to match n only if abc exists before

(?<!abc)n​

Negative Lookbehind to match n only if abc not exist before

References​

  1. ^ ↔ RegExp Assertion to negate Character Class or only match start of line

  2. | ↔ RegExp Assertion OR operator for alternative characters/expressions

  3. \B ↔ inverted RegExp Assertion to match only at not boundary of word (beginning or end of word)

  4. \b ↔ RegExp Assertion to match only at boundary of word (beginning or end of word)

  5. $ ↔ RegExp Assertion to match n expression at end of line

  6. Flag ↔ optional modifier for RegExp to config how Assertion behave on patterns