The nest.object() function in D3.js is used to apply the nest operator to the given array and returns the nested object of key-value pair.
Syntax:
nest.object( array )
Parameters: This function accepts single parameter as mentioned above and described below:
- Array: This parameter holds the array of objects.
Return Value: It returns the object.
Below are a few examples of the above function
Example 1: When no duplicate key exists.
HTML
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content= "width=device-width, initial-scale=1.0"> <style> .originalColor { height: 100px; width: 100px; } .darkerColor { height: 100px; width: 100px; } </style> </head> <body> <!-- Fetching from CDN of D3.js --> <script type="text/javascript" </script> <script> // Forming the array of objects let array = [ { car: "car1" }, { model: "model1" }, { car: "car2" }, { model: "model1" }, { car: "car3" }, { model: "model2" }, { car: "car4" }, { model: "model2" }, { car: "car5" }, { model: "model3" } ] let data = d3.nest() .key(function (d) { return d.car; }) .key(function (d) { return d.model; }) .object(array) console.log("Type is: ", typeof array) console.log(data); </script> </body> </html> |
Output:
Example 2: When duplicate keys exist and accessing those keys that does not exist when accessed, outputs undefined.
HTML
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content= "width=device-width, initial-scale=1.0"> <style> .originalColor { height: 100px; width: 100px; } .darkerColor { height: 100px; width: 100px; } </style> </head> <body> <!-- Fetching from CDN of D3.js --> <script type="text/javascript" </script> <script> // Forming the array of objects let array = [ { car: "car1" }, { model: "model1" }, { car: "car3" }, { model: "model1" }, { car: "car3" }, { model: "model2" }, { car: "car3" }, { model: "model2" }, { car: "car5" }, { model: "model3" } ] let data = d3.nest() .key(function (d) { return d.car; }) .key(function (d) { return d.model; }) .key(function (d) { return d.car; }) .object(array) console.log(data); console.log(data.car1); // Key does not exists so // output is undefined console.log(data.car2); console.log(data.car3); </script> </body> </html> |
Output:
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