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: