string.indexOf() is not working javascript

Question

I can't understand why indexOf is not working. character "İ" in İstanbul is UTF-8 character but after converting this string to lowercase it looks ok?!

var t = "İstanbul";
var q = "ist";
filterCandidate = t.toLowerCase(); //"istanbul"

var valueToMatch = filterCandidate.trim().substring(0, q.length); //"is"

console.log("filterCandidate: " + filterCandidate);
console.log("valueToMatch: " + valueToMatch);
showElement = false;
if (q.indexOf(valueToMatch) > -1) {
  showElement = true;
  
}
console.log("showElement: " + showElement);

i and lowercase İ are two different characters.

Dormilich
– Dormilich

2018-02-06 07:53:52 +00:00
Commented Feb 6, 2018 at 7:53 — Dormilich
– Dormilich, Commented Feb 6, 2018 at 7:53

Sajib Khan · Accepted Answer · 2018-02-06 08:27:31Z

5

Lowercase of İstanbul is i̇stanbul not istanbul (Note: difference between i̇ & i).

You told in comment:

In turkish "I" is "İ" and "i" is "i". This function only works only when I use "İ". Customers may use lowercsae "i" where it is not working

Solution: Use t.toLocaleLowerCase('tr-TR') instead of t.toLowerCase().

"İstanbul".toLowerCase()                // i̇stanbul 
"İstanbul".toLocaleLowerCase('tr-TR')   // istanbul

var t = "İstanbul";
var q = "ist";
filterCandidate = t.toLocaleLowerCase('tr-TR'); //"istanbul"
var valueToMatch = filterCandidate.trim().substring(0, q.length);

console.log("filterCandidate: " + filterCandidate);
console.log("valueToMatch: " + valueToMatch);
showElement = false;
if (q.indexOf(valueToMatch) > -1) {
  showElement = true;
  
}
console.log("showElement: " + showElement);

edited Feb 6, 2018 at 8:27

answered Feb 6, 2018 at 7:51

Sajib Khan

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4 Comments

Nuryagdy Mustapayev Over a year ago

I am building Turkish website, I can't change "İstanbul" to "Istanbul", I need solution for "İstanbul"

Nuryagdy Mustapayev Over a year ago

In turkish "I" is "İ" and "i" is "i". This function only works only when I use "İ". Customers may use lowercsae "i" where it is not working

Sajib Khan Over a year ago

ok, use .toLocaleLowerCase('tr-TR') instead of .toLowerCase()

Adem Tepe Over a year ago

I appreciate this. It was causing problem when filtering in jsgrid table.

Ali Shawky · Accepted Answer · 2018-02-06 07:58:45Z

0

Take care my friend the letter "İ" is not the same the letter "I" some the lowercase of the letter "İ" will never be the same as the letter "I" and the evidence is ....

 var t = "İstanbul";
 var q = "ist";
 filterCandidate = t.toLowerCase();
 filterCandidate.toUpperCase(); //this will return "İSTANBUL" again

Another evidence is try :-

filterCandidate.length // This will return 9 not 8 also the word have only 8 letters.

and another try this :-

filterCandidate[1] // It will return strange letter "̇"

answered Feb 6, 2018 at 7:58

Ali Shawky

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Comments

AL-zami · Accepted Answer · 2018-02-06 08:07:57Z

0

better create a substitute object for holding special character data.

var sub = {"İstanbul":"Istanbul"}

var data = "İstanbul";
var t = sub[data]

Rest of the code will work accordingly

answered Feb 6, 2018 at 8:07

AL-zami

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