polybius.fyi/reveal.js/node_modules/gauge/wide-truncate.js

'use strict'
var stringWidth = require('string-width')
var stripAnsi = require('strip-ansi')

module.exports = wideTruncate

function wideTruncate (str, target) {
  if (stringWidth(str) === 0) return str
  if (target <= 0) return ''
  if (stringWidth(str) <= target) return str

  // We compute the number of bytes of ansi sequences here and add
  // that to our initial truncation to ensure that we don't slice one
  // that we want to keep in half.
  var noAnsi = stripAnsi(str)
  var ansiSize = str.length + noAnsi.length
  var truncated = str.slice(0, target + ansiSize)

  // we have to shrink the result to account for our ansi sequence buffer
  // (if an ansi sequence was truncated) and double width characters.
  while (stringWidth(truncated) > target) {
    truncated = truncated.slice(0, -1)
  }
  return truncated
}