The node.count() function of D3.js library is used to count the number of leaves under a particular node and append it as a value property to the object. If the node given is itself a leaf node then the count is one.
Syntax:
node.count();
Parameters: This function does not take any parameter.
Return Value: This function returns an object.
Below given are a few examples of the function given above.
Example 1: The following example demonstrates counting leaves for the root node.
HTML
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" path1tent= "width=device-width, initial-scale = 1.0" /> </script> </head> <body> <script> // Constructing a tree var tree = { name: "rootNode", children: [ { name: "child1" }, { name: "child2", children: [ { name: "grandchild1", children: [ { name: "grand_granchild1_1" }, { name: "grand_granchild1_2" } ] }, { name: "grandchild2", children: [ { name: "grand_granchild2_1" }, { name: "grand_granchild2_2" } ] }, ] } ] }; var obj = d3.hierarchy(tree); // Using node.count() Function var count = obj.count(); console.log("The number of leaves for root" + " node are: ", count.value); </script> </body> </html> |
Output:
Example 2: The following code demonstrates counting number of leaves for any node.
HTML
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" path1tent= "width=device-width, initial-scale = 1.0" /> </script> </head> <body> <script> // Constructing a tree var tree = { name: "rootNode", // Root node children: [ { name: "child1" // Child of root node }, { name: "child2", // Child of root node children: [ { // Child of child2 name: "grandchild1", children: [ // Child of grandchild1 { name: "grand_granchild1_1" }, // Child of grandchild1 { name: "grand_granchild1_2" } ] }, { name: "grandchild2", children: [ // Child of grandchild2 { name: "grand_granchild2_1" }, // Child of grandchild2 { name: "grand_granchild2_2" } ] }, ] } ] }; var obj = d3.hierarchy(tree); var grandchild2 = obj.children[1].children[1]; // Using node.count() function var count = grandchild2.count(); console.log("The number of leaves for " + "grandchild2 are: ", count.value); </script> </body> </html> |
Output:
