How to find the length of a apex string variable inside visualforce page using javascript?

Question

I have a visualforce page and an apex controller class. There is a string variable inside the apex class and i want to find the length of that string from visualforce page using javascript.

global with sharing class SampleClass{
     public String sampleString{get; set;}

     /***rest of the code**/
}


<apex:page showHeader="false"
           controller="SampleClass">

     <!--rest of the code-->

     <script type="text/javascript">

          /**code**/

         console.log('LENGTH: ' + ({!sampleString}).length);

    </script>

</apex:page>

When I run the above code, this: LENGTH: undefined is what i am getting. And I have already checked whether there is value inside the string. sampleString is not null and it has value inside it. So, what am i doing wrong? Is there any other way to do it?

Answer 1

I believe you can use {!LEN(sampleString)}

Answer 2

If you wanted the actual string:

let sampleString = "{!JSENCODE(sampleString)}";
console.log(sampleString.length);

You need to make sure you put the string in quotes, and also use JSENCODE to make sure it doesn't get encoded incorrectly.