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>
</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>
</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> |
Output:
false false true true
Ref: https://devdocs.io/d3~5/d3-collection#map_empty