在React JS组件中,我使用来自数组的JS map函数呈现项目列表(Recipes),从App父组件传入。每个项目都有一个子列表(成分),再次使用地图功能进行渲染。
当我点击食谱标题时,我想要显示/隐藏成分的子列表。我在标题上使用onClick函数将CSS设置为none或block,但是我收到以下错误:
未捕获的TypeError:无法读取未定义的属性'openRecipe'
这是我的代码:
var App = React.createClass({
getInitialState(){
return{
showModal:false,
recipeKeys: [ ],
recipes: [ ]
}
},
addRecipeKey: function(recipe){
var allKeys = this.state.recipeKeys.slice();
var allRecipes = this.state.recipes.slice();
allKeys.push(recipe.name);
allRecipes.push(recipe);
localStorage.setObj("recipeKeys", allKeys);
this.setState({recipeKeys: allKeys, recipes: allRecipes}, function(){
console.log(this.state);
});
},
componentDidMount: function(){
var dummyRecipes = [
{
"name": "Pizza",
"ingredients": ["Dough", "Tomato", "Cheese"]
},
{
"name": "Sushi",
"ingredients": ["Rice", "Seaweed", "Tuna"]
}
]
if(localStorage.getItem("recipeKeys") === null){
localStorage.setObj("recipeKeys", ["Pizza", "Sushi"]);
dummyRecipes.forEach(function(item){
localStorage.setObj(item.name, item);
});
this.setState({recipeKeys: ["Pizza", "Sushi"], recipes: dummyRecipes}, function(){
console.log(this.state);
});
} else {
var recipeKeys = localStorage.getObj("recipeKeys");
var recipes = [];
recipeKeys.forEach(function(item){
var recipeObject = localStorage.getObj(item);
recipes.push(recipeObject);
});
this.setState({recipeKeys: recipeKeys, recipes: recipes}, function(){
console.log(this.state);
});
}
},
open: function(){
this.setState({showModal:true});
},
close: function(){
this.setState({showModal:false});
},
render: function(){
return(
<div className="container">
<h1>Recipe Box</h1>
<RecipeList recipes = {this.state.recipes} />
<AddRecipeButton openModal = {this.open}/>
<AddRecipe closeModal = {this.close} showModal={this.state.showModal} addRecipeKey = {this.addRecipeKey}/>
</div>
)
}
});
var RecipeList = React.createClass({
openRecipe: function(item){
var listItem = document.getElementById(item);
if(listItem.style.display == "none"){
listItem.style.display = "block";
} else {
listItem.style.display = "none";
}
},
render: function(){
return (
<ul className="list-group">
{this.props.recipes.map(
function(item,index){
return (
<li className="list-group-item" onClick={this.openRecipe(item)}>
<h4>{item.name}</h4>
<h5 className="text-center">Ingredients</h5>
<hr/>
<ul className="list-group" id={index} >
{item.ingredients.map(function(item){
return (
<li className="list-group-item">
<p>{item}</p>
</li>
)
})}
</ul>
</li>
)
}
)
}
</ul>
)
}
});
ReactDOM.render(<App />, document.getElementById('app'));
另外,我在这里尝试使用CSS方法,但是使用React可能有更好的方法吗?
任何人都可以帮助我吗?谢谢!
答案 0 :(得分:2)
您的问题是您在地图中丢失了此上下文...您需要将.bind(this)
添加到地图功能的末尾
{this.props.recipes.map(function(item,index){...}.bind(this))};
我回答了另一个question very similar to this here。如果你可以使用箭头功能,它会自动为你绑定哪个最好。如果你不能这样做,那么要么使用绑定,要么在地图函数中使用你在这个上下文中使用的阴影变量。
现在进行清理部分。您需要稍微清理一下代码。
var RecipeList = React.createClass({
getInitialState: function() {
return {display: []};
},
toggleRecipie: function(index){
var inArray = this.state.display.indexOf(index) !== -1;
var newState = [];
if (inArray) { // hiding an item
newState = this.state.display.filter(function(item){return item !== index});
} else { // displaying an item
newState = newState.concat(this.state.display, [index]);
}
this.setState({display: newState});
},
render: function(){
return (
<ul className="list-group">
{this.props.recipes.map(function(item,index){
var inArray = this.state.display.indexOf(index) !== -1;
return (
<li className="list-group-item" onClick={this.toggleRecipie.bind(this, index)}>
<h4>{item.name}</h4>
<h5 className="text-center">Ingredients</h5>
<hr/>
<ul className="list-group" id={index} style={{display: inArray ? 'block' : 'none'}} >
{item.ingredients.map(function(item){
return (
<li className="list-group-item">
<p>{item}</p>
</li>
)
}.bind(this))}
</ul>
</li>
)
}.bind(this))
}
</ul>
)
}
});
这可能有点复杂,您可能不想管理一系列标记以切换成分视图。我建议你为你的代码制作组件,这样它的反应更加集中,它可以更容易地切换视图。
我将用ES6语法编写这个,因为你应该使用ES6。
const RecipieList = (props) => {
return (
<ul className="list-group">
{props.recipes.map( (item,index) => <RecipieItem recipie={item} /> )
</ul>
);
};
class RecipieItem extends React.Component {
constructor(){
super();
this.state = {displayIngredients: false}
}
toggleRecipie = () => {
this.setState({displayIngredients: !this.state.displayIngredients});
}
render() {
return (
<li className="list-group-item" onClick={this.toggleRecipie}>
<h4>{item.name}</h4>
<h5 className="text-center">Ingredients</h5>
<hr/>
<ul className="list-group" style={{display: this.state.displayIngredients ? 'block' : 'none'}} >
{this.props.recipie.ingredients.map( (item) => <IngredientItem ingredient={item} /> )}
</ul>
</li>
);
}
}
const IngredientItem = (props) => {
return (
<li className="list-group-item">
<p>{props.ingredient}</p>
</li>
);
};
答案 1 :(得分:0)
您也可以使用以下内容:
override var highlighted: Bool {
get {
return super.highlighted
}
set {
if newValue {
backgroundColor = UIColor.blackColor()
}
else {
backgroundColor = UIColor.whiteColor()
}
super.highlighted = newValue
}
}