Install

$ npm install react-use-value-change --save

or

$ yarn add react-use-value-change

Direct link to npmjs.com

The problem

Quite often I find myself having complex useEffect to detect the state changes. This library helps to keep up state tracking.

It contains Three simplified methods:

• useStringValueChange
• useNumberValueChange
• useBooleanValueChange

Simple setup

const [currentValue, {setValue, resetValue, resetToCurrentValue, resetToOriginalValue}, {equals, original}] = useStringValueChange("the initial value");

• currentValue is the string current value
• original is immutable original value (until value is reset)
• equals indicates if original === currentValue
• setValue("new value") will change the currentValue, keeps original and equals is false if the new value is different form original
• resetValue() will reset original to currentValue and equals to true
• resetValue("something else") will reset currentValue and original to "something else" and equals to true
• resetToCurrentValue() will reset the original to currentValue and equals to true
• resetToOriginalValue() will reset the currentValue to original and equals to true

All the other methods follows the same pattern.

Using react input

The difference are with input listeners

• useStringInputValueChange accepts HTMLTextAreaElement | HTMLInputElement
• useNumberInputValueChange accepts HTMLInputElement (input type number)
• useBooleanInputValueChange accepts HTMLInputElement (checkbox or radio)

Those accept HTMLTextAreaElement | HTMLInputElement as setters. Which means one has to call

setValue(value: HTMLInputElement) instead of setValue(value: string) (or boolean or number)

a bit more...

There is also an umbrella method for more complex logic: useValueChange, which has to be approached carefully as it might trigger recursive rendering.

See useValueChange.test.ts how to use it.

Might be a bug, but it is not

When is used the initial value is immutable. One has to use the React useffect to reset the value.