The node.sum() function in d3.js is used to evaluate the specified value function for a particular node. The node.value property of this function contains the value returned by the specified function.
Syntax:
node.sum(value);
Parameters: This function accepts a single parameter as mentioned above and described below:
- value: This takes a function to be evaluated for each node.
Return Values: This function returns an object.
Below given are a few examples of the function given above.
Example 1:
HTML
<!DOCTYPE html> <html lang = "en"> <head>     <meta charset = "UTF-8" />     <meta name = "viewport"          path1tent = "width=device-width,                        initial-scale = 1.0"/>     <script src =     </script> </head>   <body>     <script>        // Constructing a tree         var tree={             name: "rootNode", // Root node             children: [                 {                     name: "child1", // Child of root node                     value: 2                 },                 {                     name: "child2", // Child of root node                     value: 3,                     children: [                         {                             name: "grandchild1", // Child of child2                             value: 1,                             children:[                                 {name: "grand_granchild1_1",value: 4},                                                              // Child of grandchild1                                 {name: "grand_granchild1_2",value: 5}                                                    // Child of grandchild1                             ]                         },                         {                             name: "grandchild2",                             children:[                                 {name: "grand_granchild2_1"},                                  // Child of grandchild2                                 {name: "grand_granchild2_2"}                                  // Child of grandchild2                             ]                         },                     ]                 }             ]         };           var obj = d3.hierarchy(tree);         var grandchild2=obj.children[1].children[1];                   var sum=obj.sum(d=>d.value);         console.log(sum);         console.log("The sum of value is: ",sum.value);     </script> </body> </html> |
Output:
Example 2:
HTML
<!DOCTYPE html> <html lang = "en"> <head>     <meta charset = "UTF-8" />     <meta name = "viewport"          path1tent = "width=device-width,                        initial-scale = 1.0"/>     <script src =     </script> </head> <body>     <script>     // Constructing a tree         var tree={             name: "rootNode", // Root node             children: [                 {value:1},                 {value:2},                 {value:3},                 {value:4},                 {value:5},                 {value:6},             ]         };           var obj = d3.hierarchy(tree);                   var sum=obj.sum(d=>d.value*12);         // 1 + 2 + 3 + 4 + 5 + 6 = 21*12=252         console.log(sum);         console.log("The value is: ",sum.value);     </script> </body> </html> |
Output:
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