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[React] Pass Data To Event Handlers with Partial Function Application

React to with Data Function application Event pass
2023-09-14 09:00:52 时间

In this lesson we’ll see how to pass an item’s id value in an event handler and get the state to reflect our change. We’ll also create a helper function that allows us to use partial function application to clean up the event handler code and make it more “functional”

 

Previous code:

const ActionBtns = ({ selectedBox, onBtnClick }) => (
    <nav className={classnames('nav')}>
        <RaisedButton
            label="Red"
            style={style}
            onClick={() => onBtnClick('red', selectedBox)}/>
        <RaisedButton
            label="Green"
            style={style}
            onClick={() => onBtnClick('green', selectedBox)}/>
    </nav>
);

 

We want to change the highlight code to partial applied function:

const ActionBtns = ({ selectedBox, onBtnClick }) => {
    const setGreenColor = partial(onBtnClick, 'green', selectedBox);
    const setRedColor = partial(onBtnClick, 'red', selectedBox);
    return (
        <nav className={classnames('nav')}>
            <RaisedButton
                label="Red"
                style={style}
                onClick={setRedColor}/>
            <RaisedButton
                label="Green"
                style={style}
                onClick={setGreenColor}/>
        </nav>
    );
};

 

lib:

export const partial = (fn, ...args) => fn.bind(null, ...args);

 

Test:

import {partial} from '../lib/util';

const add = (a, b) => a + b;
const addThree = (a,b,c) => a + b + c;

test('partial applies the first argument ahead of time', () => {
   const inc = partial(add, 1);
   const result = inc(2);
   expect(result).toBe(3);
});

test('partial applies the multiple arguments ahead of time', () => {
   const inc = partial(addThree, 1, 2);
   const result = inc(3);
   expect(result).toBe(6);
});

 

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