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