Question posted in 
I created the following code to extract numerical information from a user-provided string, which specifies the level or floor in a building. The goal is to accurately extract the numerical value from the input. However, the current implementation does not handle hyphenated numbers correctly. For instance, "twenty-third" is incorrectly resolved as 20 instead of 23.
function extractLevelFromString(input) {
// Normalize the input string
const normalizedInput = input.toLowerCase();
const wordToNumberMap = {
"one": 1, "first": 1,
"two": 2, "second": 2,
"three": 3, "third": 3,
"four": 4, "fourth": 4,
"five": 5, "fifth": 5,
"six": 6, "sixth": 6,
"seven": 7, "seventh": 7,
"eight": 8, "eighth": 8,
"nine": 9, "ninth": 9,
"ten": 10, "tenth": 10,
"eleven": 11, "eleventh": 11,
"twelve": 12, "twelfth": 12,
"thirteen": 13, "thirteenth": 13,
"fourteen": 14, "fourteenth": 14,
"fifteen": 15, "fifteenth": 15,
"sixteen": 16, "sixteenth": 16,
"seventeen": 17, "seventeenth": 17,
"eighteen": 18, "eighteenth": 18,
"nineteen": 19, "nineteenth": 19,
"twenty": 20, "twentieth": 20,
"twenty-one": 21, "twenty-first": 21,
"twenty-two": 22, "twenty-second": 22,
"twenty-three": 23, "twenty-third": 23,
"twenty-four": 24, "twenty-fourth": 24,
"twenty-five": 25, "twenty-fifth": 25,
"twenty-six": 26, "twenty-sixth": 26,
"twenty-seven": 27, "twenty-seventh": 27,
"twenty-eight": 28, "twenty-eighth": 28,
"twenty-nine": 29, "twenty-ninth": 29,
"thirty": 30, "thirtieth": 30,
"thirty-one": 31, "thirty-first": 31,
"thirty-two": 32, "thirty-second": 32,
"thirty-three": 33, "thirty-third": 33,
"thirty-four": 34, "thirty-fourth": 34,
"thirty-five": 35, "thirty-fifth": 35,
"thirty-six": 36, "thirty-sixth": 36,
"thirty-seven": 37, "thirty-seventh": 37,
"thirty-eight": 38, "thirty-eighth": 38,
"thirty-nine": 39, "thirty-ninth": 39,
"forty": 40, "fortieth": 40,
"forty-one": 41, "forty-first": 41,
"forty-two": 42, "forty-second": 42,
"forty-three": 43, "forty-third": 43,
"forty-four": 44, "forty-fourth": 44,
"forty-five": 45, "forty-fifth": 45,
"forty-six": 46, "forty-sixth": 46,
"forty-seven": 47, "forty-seventh": 47,
"forty-eight": 48, "forty-eighth": 48,
"forty-nine": 49, "forty-ninth": 49,
"fifty": 50, "fiftieth": 50
};
const levelRegex = /b(level|floor|on|at)?s*(d+|one|two|three|four|five|six|seven|eight|nine|ten|eleven|twelve|thirteen|fourteen|fifteen|sixteen|seventeen|eighteen|nineteen|twenty|twenty-one|twenty-two|twenty-three|twenty-four|twenty-five|twenty-six|twenty-seven|twenty-eight|twenty-nine|thirty|thirty-one|thirty-two|thirty-three|thirty-four|thirty-five|thirty-six|thirty-seven|thirty-eight|thirty-nine|forty|forty-one|forty-two|forty-three|forty-four|forty-five|forty-six|forty-seven|forty-eight|forty-nine|fifty|first|second|third|fourth|fifth|sixth|seventh|eighth|ninth|tenth|eleventh|twelfth|thirteenth|fourteenth|fifteenth|sixteenth|seventeenth|eighteenth|nineteenth|twentieth|twenty-first|twenty-second|twenty-third|twenty-fourth|twenty-fifth|twenty-sixth|twenty-seventh|twenty-eighth|twenty-ninth|thirtieth|thirty-first|thirty-second|thirty-third|thirty-fourth|thirty-fifth|thirty-sixth|thirty-seventh|thirty-eighth|thirty-ninth|fortieth|forty-first|forty-second|forty-third|forty-fourth|forty-fifth|forty-sixth|forty-seventh|forty-eighth|forty-ninth|fiftieth)(?:st|nd|rd|th)?b/gi;
const matches = normalizedInput.matchAll(levelRegex);
// Process matches
for (const match of matches) {
const levelCandidate = match[2]; // Get the potential level part
// If numeric, return directly
if (!isNaN(levelCandidate)) {
return parseInt(levelCandidate, 10);
}
// If word-based, map to a number
if (wordToNumberMap[levelCandidate]) {
return wordToNumberMap[levelCandidate];
}
}
// Return null if no level found
return null;
}
I tried this using regex pattern matching and was expecting the resolution of numbers from the input string.
3
Answers
Issue
The regular expression greedily matches string values like
"twenty"and"thirty"before matching the rest of the input when the string is"twenty-three"or"thirty-third".Solution Suggestion
Update the regular expression to include a negative lookahead to only match values like
"twenty"and"thirty"when not immediately followed by a hyphen.Example:
Here I’ve also grouped some values to reduce duplicate sub-strings.
you can use words-to-numbers package which is available to install it from npm
also, you can set the fuzzy option to true for available mistakes
One option is to place the single digit word matches (i.e
one,two, …,twenty..) at the end of the regex expression. So your regex expression will look like this:Then this will resolve the "twenty-third" to 23.