import Prism from "prismjs" if (supportsLookBehind()) { Prism.languages.env = { property: { pattern: /(.*.)(?==)/, }, string: { pattern: /(?<==)(.*.)/g, global: true, }, operator: { pattern: /=/ } } } else { Prism.languages.env = { property: { pattern: /(.*.)(?==)/, }, operator: { pattern: /=/ } } } function supportsLookBehind() { try { return /(?<==)(.*)/.test("=hello") } catch(e) { return false; } }