Extract sub string from last in a string JS

Question

I need to write JS function which returns true if string contains - depreciated in its last otherwise false.

For example:

var somestring = "string value - depreciated";

function should return true in above example.

function isDepreciated(var S)
{
    //Need to check for substring in last
    //return true or false
}

One possible solution is to use search function but that means that if - depreciated comes within string then it will also return true. I really need to find weather substring is in last or not.

Please help.

You could also do this by using [`substring`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring) to isolate the last X characters of the input and see if they match what you are looking for. — Jon, Jul 29 '13 at 08:40

score 2 · Answer 1 · edited Jul 29 '13 at 08:46

2

Add the below code in your JS

function isDepreciated(string){
   return  /(-depreciated)$/.test(string);
}

edited Jul 29 '13 at 08:46

Naveen Kumar Alone

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answered Jul 29 '13 at 08:41

Avneesh Raghav

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A regular expression is not necessary. – Ja͢ck Jul 29 '13 at 08:53
Also, should probably escape the `-`, though it's not necessarily required. – Evan Trimboli Jul 29 '13 at 08:57
Yeah! It might not be, but I find this is the shortest and robust line of code to solve this problem. – Avneesh Raghav Jul 29 '13 at 08:57
@Jack why not necessary? – meze Jul 29 '13 at 08:58
@meze I've marked this question as a duplicate of a more generic problem; you can find the solution there as well, or look at Marginean Vlad's answer. – Ja͢ck Jul 29 '13 at 08:59
@Jack that doesn't explain why not regexp. It takes less characters and probably will be faster. – meze Jul 29 '13 at 09:02
@meze I prefer finding simple functions that solve the exact problem first before moving to regular expressions as an alternative to string domain problems. This has nothing to do with speed; if it did, you'd probably be wrong though :) – Ja͢ck Jul 29 '13 at 09:10

Ghostman · Accepted Answer · 2013-07-29T08:47:48.527

1

You'll want to use the Javascript string method .substr() combined with the .length property.

function isDepreciated(var id)
{
    var id = "string value - depreciated";
    var lastdepreciated = id.substr(id.length - 13); // => "- depreciated"
    //return true or false check for true or flase
}

This gets the characters starting at id.length - 13 and, since the second argument for .substr() is omitted, continues to the end of the string.

edited Jul 29 '13 at 08:47

answered Jul 29 '13 at 08:42

Ghostman

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Does negative indexing supported in IE versions below or equal to 8? – Azeem Jul 29 '13 at 08:53
@NidaSulheri yes u can ... kindly check this link http://stackoverflow.com/questions/6918943/substr-with-negative-value-not-working-in-ie – Ghostman Jul 29 '13 at 09:13

score 1 · Answer 3 · answered Jul 29 '13 at 08:48

1

function isDepreciated(S) {
    var suffix = "- depreciated";
    return S.indexOf(suffix, S.length - suffix.length) !== -1;
}

answered Jul 29 '13 at 08:48

Marginean Vlad

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6

jantimon · Answer 4 · 2013-07-29T08:59:43.633

1

You could use currying: http://ejohn.org/blog/partial-functions-in-javascript/

Function.prototype.curry = function() {
    var fn = this, args = Array.prototype.slice.call(arguments);
    return function() {
      return fn.apply(this, args.concat(
        Array.prototype.slice.call(arguments)));
    };
  };

With the helper curry function you could create your isDepricated check:

String.prototype.isDepricated = String.prototype.match.curry(/- depreciated$/);

"string value - depreciated".isDepricated();

Or use .bind():

var isDepricated = RegExp.prototype.test.bind(/- depreciated$/);

isDepricated("string value - depreciated");

edited Jul 29 '13 at 08:59

answered Jul 29 '13 at 08:53

jantimon

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The problem being solved is more specific, so I wouldn't modify the String prototype for that. – Ja͢ck Jul 29 '13 at 08:55
You are probably right so I added a `bind` example ;) – jantimon Jul 29 '13 at 09:00
I see you're an avid fan of the JavaScript dynamism ;-) +1 for the creative aspect hehe – Ja͢ck Jul 29 '13 at 09:32

score 0 · Answer 5 · answered Jul 29 '13 at 08:48

0

function isDepreciated(S){
    return (new RegExp(" - depriciated$").test(S));
}

answered Jul 29 '13 at 08:48

Samurai

3,724
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score 0 · Answer 6 · answered Jul 29 '13 at 08:49

0

how about just use regular expression

  var myRe=/depreciated$/;
  var myval = "string value - depreciated";
  if (myRe.exec(myval)) {
    alert ('found');
  }
  else{
    alert('not found');
  }

answered Jul 29 '13 at 08:49

David Zhan Liu

474
5
8

score 0 · Answer 7 · answered Jul 29 '13 at 09:13

lots of answers are already here (the one with $ is preferred), even though i also had to write one, so it will also do your job,

var somestring = "string value - depreciated";
var pattern="- depreciated";

function isDepreciated(var s)
{
    b=s.substring(s.length-pattern.length,s.length)==pattern;
}

midhunhk · Answer 8 · 2013-07-29T08:53:35.420

-1

Ok, I haven't run this code on a browser, but this should give a basic idea of what to do. You might have to tweak some of the conditions if needed.

var search = "- depricated";
var pos = str.indexOf(search);

if(pos > 0 && pos + search.length == str.length){
    return true;
}
else{
   return false;
}

Edit: indexOf() returns the start index of the string.

edited Jul 29 '13 at 08:53

answered Jul 29 '13 at 08:40

midhunhk

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pos > 0, so that the string should be found and the next condition to see whether it is located at the end. A cleaner approach would be to do regex as posted by @Avneesh Raghav. – midhunhk Jul 29 '13 at 08:45
1

`contains` returns boolean and isn't supported in all browsers ;( – meze Jul 29 '13 at 08:49
Edited to indexOf(), thanks for spotting that. – midhunhk Jul 29 '13 at 08:54
Why the `if (foo) return true; else return false;` Why not just return the evaluation of the condition (`return foo;`)? A nitpick, but it seems rather redundant. – Evan Trimboli Jul 29 '13 at 08:58
Since the OP seems to be a student, I thought it would be easier to understand. – midhunhk Jul 29 '13 at 09:02

v2b · Answer 9 · 2013-07-29T08:50:04.780

-1

    function isDeprecated(str) {
          return ((str.indexOf("- depreciated") == str.length - "- depreciated".length) ? true : false);
    }

    isDeprecated("this")
    false

    isDeprecated("this - depreciated")
    true

    isDeprecated("this - depreciated abc")
    false

edited Jul 29 '13 at 08:50

answered Jul 29 '13 at 08:44

v2b

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Extract sub string from last in a string JS

9 Answers9