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Barney commentary #4

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33de613
Centralise model query logic for questions
barneycarroll Jun 29, 2017
9e2f188
Reduce Answer component to a point-free arrow function
barneycarroll Jun 29, 2017
2cccf54
Remove duplicate submission callback
barneycarroll Jun 29, 2017
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24 changes: 11 additions & 13 deletions Quiz/src/jsx/App.jsx
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Original file line number Diff line number Diff line change
Expand Up @@ -40,11 +40,11 @@ class App extends React.Component {

_handleSubmit() {
if (this.state.index + 1 < this.state.numberOfQuestions) {
this.setState({
this.setState({
index : this.state.index + 1
})
} else {
this.setState({
this.setState({
completed : true
})
}
Expand All @@ -64,24 +64,22 @@ class App extends React.Component {
score: (correctAnswer === selection) ? this.state.score + 1 : this.state.score,
selectionMade:false
})

}


render() {

const quizCompleted = <div>
<h1> Quiz completed ! </h1>
</div>;
const quiz = <div>
<Question
quiz={this.state.quiz}
index={this.state.index} />
<Question question={this.state.quiz[this.state.index].question} />
<Answer
handleRadio = {this._handleRadio}
buttonEnabled = {this.state.buttonEnabled}
selectionMade = {this.state.selectionMade}
options={this.state.quiz[this.state.index].options}
handleRadio = {this._handleRadio}
buttonEnabled = {this.state.buttonEnabled}
selectionMade = {this.state.selectionMade}
options={this.state.quiz[this.state.index].options}
onClickCallback = {this._handleSubmit} />
</div>;
const quizStage = !this.state.completed ? quiz : quizCompleted ;
Expand All @@ -92,10 +90,10 @@ class App extends React.Component {
<div className="questionWrapper" >
{quizStage}
</div>

</div>
)
}
}

export default App;
export default App;
54 changes: 26 additions & 28 deletions Quiz/src/jsx/components/Answer.jsx
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Original file line number Diff line number Diff line change
@@ -1,32 +1,30 @@
import React from "react";

class Answer extends React.Component{
constructor(props) {
super(props);
const Answer = props => (
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@barneycarroll barneycarroll Jun 29, 2017

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Where possible, functional components are IMO better because you get an immediate assurance that there is no lifecycle and no state, which makes it easier to reason about contents.

Un-bracketed arrow functions are even better because they are 'point-free', ie there are no internal references, just a return expression. Previously there were 2 points: declare a variable to define the options, then return a block of content which references the options. I prefer this because it's less moving parts to remember – some people dislike it on the grounds it encourages that any logic (ie the options.map) gets put in the content (I don't see a problem with that 🤷‍♂️ ).

<form>
{props.options.map((option,i) => (
<div className={`option${i}`} key={i}>
<input
type="radio"
name='rad'
id={`option_${i}`}
onChange={() => {
props.handleRadio(i)
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@barneycarroll barneycarroll Jun 29, 2017

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I prefer using anonymous event handlers in the view and calling function references within that – this avoids the necessity of re-binding class methods elsewhere because we explicitly avoid the this re-binding that comes from event handler assignment. Previously, the parent component's this binding for handleRadio was over-written by the binding here.

}}
/>
<label htmlFor={`option_${i}`}>
{option}
</label>
</div>
))}

}
<input
type="submit"
className='waves-effect waves-light btn-large submit-button visible'
onClick={props.onClickCallback}
disabled={!props.selectionMade}
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@barneycarroll barneycarroll Jun 29, 2017

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Boolean attribute expressions can be expressed like this – I love it.

/>
</form>
);

render() {

const options = this.props.options.map( (option,i) => {
return <div className={`option${i}`} key={i}>
<input type="radio" name='rad' id={`option_${i}`} onChange={this.props.handleRadio.bind(this, i)} />
<label htmlFor={`option_${i}`} > {option} </label>
</div>
});

return(
<form onSubmit={this.props.onClickCallback}>
{options}
<input
type="submit"
className='waves-effect waves-light btn-large submit-button visible'
onClick={this.props.onClickCallback}
disabled={ this.props.selectionMade ? '' : 'disabled'} />
</form>
)
}
}


export default Answer;
export default Answer;
19 changes: 7 additions & 12 deletions Quiz/src/jsx/components/Question.jsx
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Original file line number Diff line number Diff line change
@@ -1,17 +1,12 @@
import React from "react";

const Question = (props) =>{

const QuestionObejct = props.quiz[props.index];

return(
<div className="questionWrapper" >
<div className='questions'>
{QuestionObejct.question}
</div>
const Question = ({question}) => (
<div className="questionWrapper" >
<div className='questions'>
{question}
</div>
)
}
</div>
);


export default Question;
export default Question;