Limiting string up to a specified length in JavaScript

Problem

We are required to write a JavaScript function that takes in a string and a number. Our function should return the truncated version of the given string up to the given limit followed by "..." if the result is shorter than the original string otherwise our function should return the same string if nothing was truncated.

Example

Following is the code −

const str = 'Testing String';
const num = 8;
const limitString = (str = '', num = 1) => {
   const { length: len } = str;
   if(num < len){
      return str.slice(0, num) + '...';
   }else{
      return str;
   };
};
console.log(limitString(str, num));

Output

Following is the console output −

Testing ...