RunKit + npm: xregexp

var xregexp = require("xregexp") // /[\u0000-\u001f\u0022\u005c\ud800-\udfff]|[\ud800-\udbff](?![\udc00-\udfff])|(?:[^\ud800-\udbff]|^)[\udc00-\udfff]/ const STR_ESCAPE = xregexp( `[\u0000-\u001f\u0022\u005c\ud800-\udfff] # chars A - G | [\ud800-\udbff] # chars H - J (?![\udc00-\udfff]) # BUT NOT something else | (?:[^\ud800-\udbff]|^) # some explantation [\udc00-\udfff] # something else ` , 'x' )