map函数在React中不起作用

Question

I am new to React JS, I was testing out some functions in fiddler. I am not sure why I get an error pointing to the map function. I am not able to render the array i defined.

Relevant snippet:

      {this.props.data.productSpecs.map(function(productSpec){
        <b>Category Name:</b> {productSpec};
      })}

Full code:

var productCategory = {
    productName: 'SamamgaTV1',
  productCategory: 'Television', 
  productSpecs: ['32inch','black','hd']
};

var ProductComponent = React.createClass({
  render: function() {
    return( <div>
                        <h2>Product</h2>
              <b>Product Name:</b> {this.props.data.productName}
              <h2>Category</h2>
              <b>Category Name:</b> {this.props.data.productCategory}
              <h2>Specs</h2>
              {this.props.data.productSpecs.map(function(productSpec){
                <b>Category Name:</b> {productSpec};
              })}
           </div>);
  }
});

ReactDOM.render(
  <ProductComponent data={productCategory} />,
  document.getElementById('container')
);

Answer 1

First you missed to return , then you must return ONE element. Here you return a <p> and a TextNode

Moreover you need to provide a unique key.

Try with this :

{this.props.data.productSpecs.map(function(productSpec, i){
        return <span key={i}><b>Category Name:</b> {productSpec}</span>;
})}

Answer 2

You need to return value from map handler.

{this.props.data.productSpecs.map(function(productSpec){
    return (<span><b>Category Name:</b> {productSpec}<span>);
})}

If you do not want to (or can't in some situations) wrap content in span, you can create & return fragment (very handy)

const createFragment = require('react-addons-create-fragment');

{this.props.data.productSpecs.map(function(productSpec){
    return createFragment({
        bold: <b>Category Name:</b>,
        spec: productSpec,
    });
})}

Answer 3

可能是您正在使用字符串，因此您必须使用split方法并传入一个空字符串，例如myValue.split（''）。map（）;