How to modify a value by selection in d3.js?

@rollin 

To modify a value by selection in d3.js, you can follow these steps:

1. Select the element(s) you want to modify using the d3.select() or d3.selectAll() method. This method accepts a CSS selector or a DOM element.
2. Access the property or attribute of the selected element(s) that you want to modify using the .property() or .attr() method.
3. Update the value of the property or attribute using the .property() or .attr() method again, passing the new value as an argument.

Here's an example that demonstrates how to modify the value property of an input element by selection in d3.js:

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// Select the input element using its ID
const input = d3.select("#myInput");

// Get the current value of the input element
const currentValue = input.property("value");

// Modify the value of the input element
input.property("value", "New Value");

In the example above, the d3.select() method selects the input element with the ID "myInput". Then, the .property() method is used to get the current value of the input element and to modify its value to "New Value" using the same method.

Note that if you are working with SVG elements, you may need to use .attr() instead of .property() to modify certain attributes, such as d for path elements or cx and cy for circle elements.