Underscore.js _.partial() Function

Namachila October 31, 2025

0 1 1 minute read

The _.partial() function is used to apply partially a function by filling in any number of its arguments, without changing its dynamic value.

Syntax:

_.partial(function, *arguments)

Parameters: This function accept two parameters as mentioned above and described below:

function: The function that need to be executed.
arguments: This parameter needs to add some symbols between elements.

Return Value: This function returns the result of partially executed function.

Below examples illustrate the _.partial() Function in Underscore.js:
Example 1:

<!DOCTYPE html> 
<html> 
  
<head> 
    <script type="text/javascript" src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <script type="text/javascript"> 
  
        var product = function (num1, num2) { 
            return num1 * num2; 
        }; 
  
        prod = _.partial(product, 15); 
        console.log(prod(18)); 
    </script> 
</body> 
  
</html> 

Output:

Example 2:

<!DOCTYPE html> 
<html> 
  
<head> 
    <script type="text/javascript" src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"> 
    </script> 
</head> 
  
<body> 
    <script type="text/javascript"> 
  
        var sum = function (num1, num2, num3) { 
            return num1 + num2 + num3; 
        }; 
  
        sum = _.partial(sum, 15, 25); 
        console.log(sum(18)); 
    </script> 
</body> 
  
</html> 