Needing to do some pattern matching with javascript

Question 1

I have a long string that a user entered. Using javascript I want to get the text of the first sentence IF it ends in a question mark. Is there a simple way I can do this?

For example:

var myText1 = "What is your name? My name is Michelle."

I need to return: "What is your name"

var myText2 = "this is a test. this is a test."

I need to return: "n/a"

Question 2

Depends how reliable you want it to be. What constitutes a sentence for you?

Question 3

Must be the first block of text that ends in a ". " or "? " I don't need to do a very strong test so for example even the string "abc 1. and xx." would be a sentence "abc 1"

Question 4

Then how would you handle"Btw. what's your name?"? (abbreviations in general)

Question 5

I would handle it as "btw." which returns "n/a"

Question 6

Or "How are you today Mr. Willoughsby?"

Question 7

Regex to the rescue:

var res = str.match(/^([^.]+)\?/);var output = (res == null) ? 'n/a' : res[1];

Question 8

I'm confused as to how practical this would be, but this should work.

var text = "this is a question? this is some text.";var split1 = text.split(/[.?]+/); // splits the text at "." and "?"var split2 = text.split(/[?]+/); // splits the text at "?"// if the first element in both arrays is the same, the first sentence is a question.var result = (split1[0] == split2[0]) ? split1[0] : "n/a";

Question 9

Wouldn't this fail if text doesn't have either. and? (eg: if text was"hello", result would be"hello")

Question 10

Absolutely, although the OPs definition of a sentence was "Must be the first block of text that ends in a . or ?". I personally think the whole premise is flawed and that a much more sophisticated approach is needed. But this works for what was asked.

Question 11

According to US English grammar rules, sentences end in.,? or!, but if the sentence ends in a quotation then a" will follow(He said to me, "How are you doing?"). Does this count as a question? The sentence itself is a statement quoting a question, so I'll assume the answer is no. This makes it easier since we only have to account for? not followed by a".

Given the above, here's my solution:

function startIsQuestion( str ) {  var m = str.match(/^[^.!]+[?][^"]/);  if (!m ||       m[0].indexOf('.') >= 0 ||      m[0].indexOf('!') >= 0 ||      m[0].indexOf('?"') >= 0) return "n/a";  return m[0];}

I don't think it's completely robust, but I'm not sure of your complete requirements and it should give you a good start.

See demo

Aillyn 23.9k24 gold badges63 silver badges88 bronze badges · Accepted Answer · 2011-08-28 18:05:16Z

2

Regex to the rescue:

var res = str.match(/^([^.]+)\?/);var output = (res == null) ? 'n/a' : res[1];

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editedAug 28, 2011 at 18:05

answeredAug 28, 2011 at 17:57

Aillyn

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Needing to do some pattern matching with javascript

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