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Underscore.js _.before() function

  • Last Updated : 16 Jul, 2020

_.before() function in underscore.js is used to call a particular function a particular number of times. It uses a count variable that keeps the track of number of times the function is called.

Syntax:

_.before(count, function)

Parameters:

  • Count: It is the number of times a function is to be called.
  • Function: It is the function that runs the count times.

Return: This function returns the the count of the function call.

Note: Please Link the underscore CDN before using this code directly in the browser through the code.



Example 1:




<!DOCTYPE html> 
<html
  <head
    <script src =  
    </script
  </head
  <body
    <script>
      let print=()=>{
        console.log("geeks for geeks")
      }
      console.log(`Print function will only run 3 times`)
      //the print function cannot run more than 3 times
      count=_.before(4, print);
      //calling count function more than 3 times
      count();
      count();
      count();
      count();
      count();
      count();
      count();
    </script>
  </body
</html>

Output:

Example 2:

It is clear from the example that if The button is clicked again and again than print function will not be working as it as already reached the count.




<!DOCTYPE html> 
<html
  <head
    <script src =  
    </script
   </head
  <body
    <button id="btn">button</button>
    <script>
      let print=()=>{
        console.log("geeks for geeks")
      }
      //the print function cannot run more than 99 times
      count=_.before(100, print);
      //calling count function more than 99 times
      let btn=document.querySelector("#btn");
      let run=()=>{
      console.log(`Print function will only run 99 times`)
        for(let i=0; i<5000; i++){
          count()
        }
      }
      btn.addEventListener("click", run)
    </script>
  </body
</html>

Output:




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