Running a loop to animate in a callback function

Question

Running a loop to animate in a callback function

Inside the function updateMapColor, the colors of a world map change based on the input year. I have tried to animate the color change over multiple years by calling updateMapColor, but it is not working.

Do I need to incorporate setInterval? If so, could someone please explain why? What might be causing the issue?

d3.select('body').append('button').attr({
    class: "button",
    id: "animateMap"
})
    .text("Animate the map")
    .on("click", function (d) {
        for (i = 0; i < yearArray.length; i++) {
            updateMapColor(yearArray[i]);
        }
    })

var updateMapColor = function (y) {
    year = y;
    var rankingList = {};
    coloredWorldMap.transition().duration(700).attr('fill', function (d) {
        a = d;
        x = d3.values(tennis).filter(function (d) {
            return (d.DATE == year);
        });
        rankingList = x;

        x = d3.values(x).filter(function (d) {
            return (d.COUNTRY_ID == a.id);
        });

        if (x.length != 0) {
            if (x[0].COUNT == 0) {
                return "#fff";
            }
            else {
                return colorScale(x[0].COUNT);
            }
        }

        else {
            return '#fff';
        }

        return colorScale(x[0].COUNT);
    });
}

javascript d3.js

Answer 1

Answer №1

If you've ever tackled the challenge of calling a function with a delay inside a JavaScript for loop, you'll recognize this classic problem.

The issue at hand is quite straightforward: the for loop executes almost instantly (within milliseconds for even just a hundred iterations), causing all calls to the updateMapColor function to occur nearly simultaneously.

Luckily, there are various solutions to resolve this dilemma. One effective approach involves leveraging an Immediately Invoked Function Expression (IIFE):

(function loop(i) {
    if (i++ >= (yearArray.length - 1)) return;
    setTimeout(function() {
        updateMapColor(i);
        loop(i)
    }, 500)
})(-1);

Breaking it down:

This IIFE initiates with i = -1. Upon each iteration, i increments (via i++)—effectively starting at 0, akin to your original for loop—and evaluates whether it exceeds or matches yearArray.length - 1. If so, the loop function exits. Otherwise, a setTimeout is triggered, invoking both updateMapColor and the recursive loop function.

For a hands-on demonstration, observe the script below, operating with a setInterval duration of 0.5 seconds:

var yearArray = d3.range(20);

(function loop(i) {
    if (i++ >= (yearArray.length - 1)) return;
    setTimeout(function() {
        updateMapColor(i);
        loop(i)
    }, 500)
})(-1);

function updateMapColor(index){
console.log("The function was called with i = " + index);
}

<script src="https://d3js.org/d3.v4.min.js"></script>

PS: For a smoother solution, consider implementing a series of D3 transitions.

Answer 2

If you've ever tackled the challenge of calling a function with a delay inside a JavaScript for loop, you'll recognize this classic problem.

The issue at hand is quite straightforward: the for loop executes almost instantly (within milliseconds for even just a hundred iterations), causing all calls to the updateMapColor function to occur nearly simultaneously.

Luckily, there are various solutions to resolve this dilemma. One effective approach involves leveraging an Immediately Invoked Function Expression (IIFE):

(function loop(i) {
    if (i++ >= (yearArray.length - 1)) return;
    setTimeout(function() {
        updateMapColor(i);
        loop(i)
    }, 500)
})(-1);

Breaking it down:

This IIFE initiates with i = -1. Upon each iteration, i increments (via i++)—effectively starting at 0, akin to your original for loop—and evaluates whether it exceeds or matches yearArray.length - 1. If so, the loop function exits. Otherwise, a setTimeout is triggered, invoking both updateMapColor and the recursive loop function.

For a hands-on demonstration, observe the script below, operating with a setInterval duration of 0.5 seconds:

var yearArray = d3.range(20);

(function loop(i) {
    if (i++ >= (yearArray.length - 1)) return;
    setTimeout(function() {
        updateMapColor(i);
        loop(i)
    }, 500)
})(-1);

function updateMapColor(index){
console.log("The function was called with i = " + index);
}

<script src="https://d3js.org/d3.v4.min.js"></script>

PS: For a smoother solution, consider implementing a series of D3 transitions.

Running a loop to animate in a callback function

Answer №1

Similar questions

AngularFire and Ionic - There is no data being sent to the server from the form

Enhancing React Functionality: Increasing React State Following an If Statement

JavaScript keydown event for rotating images

Using Previous and Next Buttons in Bootstrap Tabs for Form Navigation

Navigating to a different state key within a state object in React - a simple guide

How come defining the state using setTimeout does not display the accurate properties of a child component?

The property this.props.Values is not defined

The animation unexpectedly resets to 0 just before it begins

Ways to avoid scrolling on a fixed element

ReactJs: difficulty in resetting input field to empty string

What's with the increased verbosity of mongoose query result objects in the latest version?

The most efficient method of assigning array indexes to boolean values within an object

Streaming data from MongoDB to a file using Node.js

Is it viable to create an onClick event for the text content within a text area?

I possess a webpage containing a div element that is loaded dynamically through ajax

Experience the impact of a lagging network connection on Chrome extensions through the power of React-NextJS

Issues with updating $setValidity from a directive in AngularJS

Ways to retrieve the value of a variable beyond its scope while using snapshot.foreach

Issue with triggering onchange action for Multiple File Upload functionality

"Scotchy McScotchface's to-do list application powered