Building a Multi-Range Slider in React From Scratch

Creating a complex component in React from scratch can be challenging at times. But if you really want to hone your JavaScript and CSS skills, then it is definitely worth the try.

This article solely focuses on building a multi-range slider without using a third-party library.

Check out the demo shown below.

Creating the Basics

Let's create a MultiRangeSlider.js component file and add the JSX given below.

const MultiRangeSlider = () => {

return (
    <>
      <input
        type="range"
        min="0"
        max="1000"
        className="thumb thumb--zindex-3"
      />
      <input
        type="range"
        min="0"
        max="1000"
        className="thumb thumb--zindex-4"
      />
    </>
  );
};

export default MultiRangeSlider;

In the above code, the first input range tag will be used as the left thumb for sliding and the second one will be used as the right thumb.

In the next step, let's get rid of the default appearances of both the sliders using CSS and redesign them.

Redesigning the Component

We need to create the track and range bars for the slider. Add the code given below right after the input tags.

<div className="slider">
   <div className="slider__track" />
   <div className="slider__range" />
</div>

Now, create a multiRangeSlider.css file and add the styles.

.slider {
  position: relative;
  width: 200px;
}

.slider__track,
.slider__range {
  border-radius: 3px;
  height: 5px;
  position: absolute;
}

.slider__track {
  background-color: #ced4da;
  width: 100%;
  z-index: 1;
}

.slider__range {
  background-color: #9fe5e1;
  z-index: 2;
}

/* Removing the default appearance */
.thumb,
.thumb::-webkit-slider-thumb {
  -webkit-appearance: none;
  -webkit-tap-highlight-color: transparent;
}

.thumb {
  pointer-events: none;
  position: absolute;
  height: 0;
  width: 200px;
  outline: none;
}

.thumb--zindex-3 {
  z-index: 3;
}

.thumb--zindex-4 {
  z-index: 4;
}

/* For Chrome browsers */
.thumb::-webkit-slider-thumb {
  background-color: #f1f5f7;
  border: none;
  border-radius: 50%;
  box-shadow: 0 0 1px 1px #ced4da;
  cursor: pointer;
  height: 18px;
  width: 18px;
  margin-top: 4px;
  pointer-events: all;
  position: relative;
}

/* For Firefox browsers */
.thumb::-moz-range-thumb {
  background-color: #f1f5f7;
  border: none;
  border-radius: 50%;
  box-shadow: 0 0 1px 1px #ced4da;
  cursor: pointer;
  height: 18px;
  width: 18px;
  margin-top: 4px;
  pointer-events: all;
  position: relative;
}

Adding Props, State and Refs

Defining the Props

The component requires two props — min and max. It can also take a third prop onChange to retrieve the min and max values whenever their state changes.

import PropTypes from "prop-types";

// Call the props
const MultiRangeSlider = ({ min, max, onChange }) => {};

// Set the type of each prop
MultiRangeSlider.propTypes = {
  min: PropTypes.number.isRequired,
  max: PropTypes.number.isRequired,
  onChange: PropTypes.func.isRequired
};

Adding State

Since the minimum and maximum values need to keep changing while sliding, the component also requires two state variables — minVal and maxVal.

import { useState } from "react";

// Creating the state variables
const [minVal, setMinVal] = useState(min);
const [maxVal, setMaxVal] = useState(max);

Creating Refs

We also need to create refs to store the minimum and maximum values. I shall come back to explaining this at a later stage when we use them.

import { useRef } from "react";

// Creating the refs
const minValRef = useRef(null);
const maxValRef = useRef(null);

Now that our props, refs, and state variables have been defined, let's use them in our input tags.

We first need to add the classnames library since we need to specify a conditional class.

$ yarn add classnames

Add the below class to the multiRangeSlider.css file.

.thumb--zindex-5 {
  z-index: 5;
}

Import the classnames library at the top and use it in the input tag given below.

<input
   type="range"
   min={min}
   max={max}
   value={minVal}
   ref={minValRef}
   onChange={(event) => {
     const value = Math.min(+event.target.value, maxVal - 1);
     setMinVal(value);
     event.target.value = value.toString();
   }}
   className={classnames("thumb thumb--zindex-3", {
     "thumb--zindex-5": minVal > max - 100
   })}
/>
<input
   type="range"
   min={min}
   max={max}
   value={maxVal}
   ref={maxValRef}
   onChange={(event) => {
     const value = Math.max(+event.target.value, minVal + 1);
     setMaxVal(value);
     event.target.value = value.toString();
   }}
   className="thumb thumb--zindex-4"
/>

So, let's figure out what the onChange event of the first input tag is doing.

The Math.min method takes two arguments:

• event.target.value, i.e., the current value, which is converted to type number using the unary plus operator (+).
• maxVal - 1, maintains a difference of one between minVal and maxVal.

The Math.min method returns the minimum value and stores it in the variable value. The setMinVal method then uses this variable to set the state of minVal. This is done to make sure that minVal does not exceed maxVal.

The onChange event of the second input tag functions in the same way. In this case, maxVal does not fall below minVal.

The class thumb--zindex-5 is conditionally applied to the left thumb to be able to move the thumb from the extreme right end. The image shown below explains this more clearly.

Changing the Range Width

We first need to access the <div className="slider__range" /> in order to change its width. React's useRef hook will help us achieve this.

// Create a ref
const range = useRef(null);

// Attach the ref
<div ref={range} className="slider__range" />

Whenever the minVal and maxVal state variables change, our component needs to re-render and decrease or increase the width of the range accordingly. We will use the useEffect hook to accomplish this.

import { useCallback, useEffect } from "react";

// Convert to percentage
const getPercent = useCallback(
    (value) => Math.round(((value - min) / (max - min)) * 100), [min, max]
);

// Set width of the range to decrease from the left side
useEffect(() => {
  if (maxValRef.current) {
    const minPercent = getPercent(minVal);
    const maxPercent = getPercent(+maxValRef.current.value); 

    if (range.current) {
      range.current.style.left = `${minPercent}%`;
      range.current.style.width = `${maxPercent - minPercent}%`;
    }
  }
}, [minVal, getPercent]);

// Set width of the range to decrease from the right side
useEffect(() => {
  if (minValRef.current) {
    const minPercent = getPercent(+minValRef.current.value);
    const maxPercent = getPercent(maxVal);

    if (range.current) {
     range.current.style.width = `${maxPercent - minPercent}%`;
    }
  }
}, [maxVal, getPercent]);

// Get min and max values when their state changes
useEffect(() => {
    onChange({ min: minVal, max: maxVal });
}, [minVal, maxVal, onChange]);

In the first useEffect hook, maxValRef.current.value is used instead of the state variable maxVal because we only need the range width to change when minVal changes. If maxVal was used, ESLint would throw a warning asking us to include it in the dependency array since it is a state variable and not a reference variable.

By default, the width of any div tag would decrease or increase from the right side. To reverse this functionality, we use the left property in CSS in the first useEffect hook.

Displaying the Range Values

Let's create two more divs to display minVal and maxVal. Place them after <div ref={range} className="slider__range" />.

<div className="slider__left-value">{minVal}</div>
<div className="slider__right-value">{maxVal}</div>

Add the required CSS to the multiRangeSlider.css file.

.slider__left-value,
.slider__right-value {
  color: #dee2e6;
  font-size: 12px;
  margin-top: 20px;
  position: absolute;
}

.slider__left-value {
  left: 6px;
}

.slider__right-value {
  right: -4px;
}

And that's all the code you need to build the MultiRangeSlider component.

Use the component in the App.js file and set the min and max values.

 <MultiRangeSlider
     min={0}
     max={1000}
     onChange={({ min, max }) => console.log(`min = ${min}, max = ${max}`)}
 />

We now have a multi-range slider built from scratch without using a library!

For all the TypeScript fans out there, here's the link to the TypeScript version: Multi-Range Slider (TypeScript)

Thanks for giving it a read.

Happy coding!

Comments

[Peter Cole]

Nice job, really helpful article!

Little heads up for people looking at this implementation, I noticed that the outline: none plus lack of a focus state on the thumb makes this not good for keyboard users as you can't tell it's focused at all, so a bit of work would be needed to make it clear when each thumb has focus

[JuanPastenCastillo]

Thanks so much Sandra! I have to implement this and your code was very very helpful. I did a couple of changes in order to make get my final results in all the browser, I'll be very glad if you can tell me what do you think about it. Thanks so much for all!

codesandbox.io/s/bold-wildflower-q...

[wakywayne]

This was wonderful!!! I had to remove the functions from the useEffect dependency arrays, but after that this worked wonders!

[Mohamed Amine Terbah]

Great job this helped me meet the deadline of my task, thank you.

[wakywayne]

Hey I am trying to use your slider with react-tables so your slider is acting as a filter. This requires the slider to be in a <th>. This poses an issue because on smaller screen sizes the slider seems to grow outside of the<th>that it is inside. How can I control the horizontal size of the slider so it is smaller? Everything I do seems to fail miserably. Thanks in advance for anyone who helps :)

[wakywayne]

I figured it out if you wrap the react-table filter display function in a div with position relative, you can then set the width of the other fields to 100 and they won't overlap. Notice the w-100 class.

<div className="mt-3 pb-5 w-100">
<div className="slider w-100">
<div className="slider__track" />
<div ref={range} className="slider__range" />
<div className="slider__left-value text-dark">{minVal}</div>
<div className="slider__right-value text-dark">{maxVal}</div>
</div>
<input
type="range"
min={minWeight}
max={maxWeight}
value={minVal}
ref={minValueRef}
onChange={(event) => {
const value = Math.min(Number(event.target.value), maxVal - 1);
setMinVal(value);
event.target.value = value.toString();
}}
className={"thumb thumb--zindex-3 w-100"}
/>
<input
type="range"
min={minWeight}
max={maxWeight}
value={maxVal}
ref={maxValueRef}
onChange={(event) => {
const value = Math.max(+event.target.value, minVal + 1);
setMaxVal(value);
event.target.value = value.toString();
}}
className="thumb thumb--zindex-4 w-100"
/>
</div>


[Ashish-21]

Thanks! It was good learning of react and usage of ref.

Can you please elloborate z-index condition in first input tag : zIndex: minVal > max - 100 && "5" . Also it is not working when we are using react with typescript.

Thanks!

[Sandra Lewis]

Check out this image: dev-to-uploads.s3.amazonaws.com/up...
I've explained the reason why the inline z-index style is needed over there, hope that clears your doubt.

I did this initially with TypeScript and it worked. The only difference is you got to specify the types.
Here's the TypeScript version: codesandbox.io/s/b9l0g

[Ashish-21]

Thank you so much for explanation and typescript code.It was great learning experience.😊

[Sandra Lewis]

You're welcome, glad it helped 😊

[tw1t611]

I've got two hints for you, add them if you like. :)

This callback is actually just a function call.
// Convert Number to percentage
function getPercent(value) {
return Math.round(((value - min) / (props.max - min)) * 100);
}

You don't need refs for the inputs, if you set the value directly onChange.
onChange={(e) => {
const value = Math.min(Number(e.target.value), maxVal);
e.target.value = value;
setMinVal(value);
}

[Sandra Lewis]

I did try using getPercent as a simple function initially, but ended up getting the below ESLint warning.

The 'getPercent' function makes the dependencies of useEffect Hook change on every render. To fix this, wrap the definition of 'getPercent' in its own useCallback() Hook.

You are right about not using refs in the onChange events. I've made the changes above. Thank you for pointing that out.

[Vaibhav Khulbe]

Good one! I like the use of ref here. 😁

[Sandra Lewis]

Thank you 😁

[chetanneware93]

Hey! It was good to learn something new using react.
I have one observation if you see in Mozilla browser the thumb looks behind the slider range(working fine in Chrome), i have dig into this but couldn't found the fix, can you please help me with this.
checkout this image for Mozilla
dev-to-uploads.s3.amazonaws.com/up...

Chrome:
dev-to-uploads.s3.amazonaws.com/up...

[Sandra Lewis]

Oh yes, I built this component only for Chrome browsers, forgot to mention that.
I've updated the CSS above and have included Firefox support. You need to use the pseudo-element ::-moz-range-thumb to support Firefox browsers.

Add the below code and it should work.

.thumb::-moz-range-thumb {
  background-color: #f1f5f7;
  border: none;
  border-radius: 50%;
  box-shadow: 0 0 1px 1px #ced4da;
  cursor: pointer;
  height: 18px;
  width: 18px;
  margin-top: 4px;
  pointer-events: all;
  position: relative;
}

Also, make sure you don’t combine .thumb::-moz-range-thumb with .thumb::-webkit-slider-thumb even though the styles remain the same. Add these classes along with its styles separately, or else it won’t work.