调用的时候提示callback.call is not a function，新手求解

Question

findFolders (data, callback) {
    let postData = ''
    if (data.hasOwnProperty('id')) {
      postData ? postData = postData + '&id=' + data.id : postData = postData + 'id=' + data.id
    }
    if (data.hasOwnProperty('cache')) {
      postData ? postData = postData + '&cache=' + data.cache : postData = postData + 'cache=' + data.cache
    }
    if (data.hasOwnProperty('global')) {
      postData ? postData = postData + '&global=' + 'true' : postData = postData + 'cache=' + data.cache
    }
    ajax.get({
      url: '/folder/findFolders?' + postData,
      success (d) {
        callback && callback.call(this, d)
      }
    })
  }

Answer 1

请确定你传入的callback是function类型

Answer 2

if (typeof callback === "function") callback.call(this, d)