pinafore/routes/_utils/replaceEmoji.js

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import { getEmojiRegex } from './emojiRegex'
// \ufe0f is a variation selector, which seems to appear for some reason in e.g. ™
let NON_EMOJI_REGEX = new RegExp('^[0-9#*™®\ufe0f]+$')
// replace emoji in HTML with something else, safely skipping HTML tags
export function replaceEmoji (string, replacer) {
let output = ''
let leftAngleBracketIdx = string.indexOf('<')
let currentIdx = 0
let emojiRegex = getEmojiRegex()
function safeReplacer (substring) {
// emoji regex matches digits and pound sign https://git.io/fpl6J
if (substring.match(NON_EMOJI_REGEX)) {
return substring
}
return replacer(substring)
}
while (leftAngleBracketIdx !== -1) {
let substring = string.substring(currentIdx, leftAngleBracketIdx)
output += substring.replace(emojiRegex, safeReplacer)
let rightAngleBracketIdx = string.indexOf('>', leftAngleBracketIdx + 1)
if (rightAngleBracketIdx === -1) { // broken HTML, abort
output += string.substring(leftAngleBracketIdx, string.length)
return output
}
output += string.substring(leftAngleBracketIdx, rightAngleBracketIdx) + '>'
currentIdx = rightAngleBracketIdx + 1
leftAngleBracketIdx = string.indexOf('<', currentIdx)
}
output += string.substring(currentIdx, string.length).replace(emojiRegex, safeReplacer)
return output
}