在JSX中的嵌套映射函数内部反映JS打印数据

Question

I am trying to print data inside a nested map function. For some reason it does not print anything. here is what I have:

  {dataFormat.protein_questions.map((item, index) => (
        <div key={_.uniqueId()} className="item">
         <div className="inline fields">
           <Field
              onChange={handleChange}
              name={`protein_question[${index}].units_of_measurement`}
              component="select"
              className="ui dropdown2"
              required>

                 {item.typing_methods.map((method, methodIndex) => {
                    method.unitsOfMeasurement.map((unit, unitIndex) => (
                       <option value={unit.title}>{unit.title}</option>
                    ));
                 })}

          </Field>
         </div>
       </div>
  ))}

The options are not printing any data inside the select for some reason. When I console log the data inside the nested loop it shows fine. Anyone know why this is happening?

By the way this is inside my render function in a JSX view file.

Answer 1

It looks like you forgot return before method.unitsOfMeasurement... :

{item.typing_methods.map((method, methodIndex) => {
  return method.unitsOfMeasurement.map((unit, unitIndex) => (
    <option value={unit.title}>{unit.title}</option>
  ));
})}