D3.js | d3.map.empty() Function

Last Updated : 28 Jun, 2019

The map.empty() function in D3.js is used to return true if the created map containing zero entries otherwise returns false.

Syntax:

map.empty();

Parameters: This function does not accept any parameter.

Return Value: This function returns true if the map is empty otherwise returns false.

Below programs illustrate the d3.map.empty() function in D3.js:

Example 1:

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        d3.map.empty() Function 
    </title> 
      
    <script src = "https://d3js.org/d3.v4.min.js"></script> 
</head> 
  
<body> 
    <script> 
          
        // Creating a map 
        var map1 = d3.map({"a": 1}, {"b": 2}, {"c": 3}); 
        var map2 = d3.map(); 
      
        // Calling the map.empty() function 
        A = map1.empty(); 
        B = map2.empty(); 
          
        // Getting the result whether the maps are empty or not 
        console.log(A); 
        console.log(B); 
    </script> 
</body>     
  
</html> 

Output:

false
true

Example 2:

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        d3.map.empty() Function 
    </title> 
      
    <script src = "https://d3js.org/d3.v4.min.js"></script> 
</head> 
  
<body> 
    <script> 
          
        // Creating a map 
        var map1 = d3.map({"a": 1}, {"b": 2}, {"c": 3}); 
        var map2 = d3.map({"GFG": 5}); 
        var map3 = d3.map({}); 
        var map4 = d3.map(); 
        
        // Calling the map.empty() function 
        A = map1.empty(); 
        B = map2.empty(); 
        C = map3.empty(); 
        D = map4.empty(); 
        
        // Getting the result whether 
        // the maps are empty or not 
        console.log(A); 
        console.log(B); 
        console.log(C); 
        console.log(D); 
    </script> 
</body>     
  
</html> 