JS 为各种相似文件返回单一文件类型（例如 'mp4' || 'm4v' = 'MOV'）

Question

I have a populateTable function, and I'm trying to combine a couple of different file types that might be read from the JSON file into one display type. In this case mp4 and m4v into MOV — I'm not getting any errors, but everything is turning up undefined in the table.

function populateTable() {
    
    function setGenericType(type) {
        if(type == 'mp4' || type == 'm4v')  {
            return 'MOV'
        }
    }

    for (const d of data) {
        $("#contents").append(`<tr>
            <td>${d.title}</td>
            <td>${d.year}</td>
            <td>${setGenericType(d)}</td>
          </tr>`)   
    }
}

Any ideas? An example of the JSON from data.js:

{
    "title":"Arc Transition",
    "year":2016,
    "type":"mp4"
}

Answer 1

You pass the whole data object into your setGenericType function, but compare the parameter to strings, so they will never match. And if there's no match of type, the function returns undefined .

So either treat the parameter of your function as the object you are passing to it

function setGenericType(d) {
  if(d.type == 'mp4' || d.type == 'm4v')  {
    return 'MOV'
  }
}

Or just pass the type of the object to your function and keep the function as it is

for (const d of data) {
  $("#contents").append(`<tr>
    <td>${d.title}</td>
    <td>${d.year}</td>
    <td>${setGenericType(d.type)}</td>
   </tr>`)   
}