如何限制基于JS浏览器的API应用程序?

时间:2019-07-01 15:21:21

标签: javascript ajax setinterval throttling

这是我的代码:

var idsClean = [];

function id(file) {
  return new Promise((resolve, reject) => {
    reader = new FileReader();
    reader.onload = function(e) {
      parsedLines = e.target.result.split(/\r|\n|\r\n/);
      resolve(parsedLines);
    };
    reader.readAsText(file);
  });
}

document.getElementById('fileInput').addEventListener('change', getReleasesFromFile);

function getReleasesFromFile(event) {
  const file = event.target.files[0]
  if (file === undefined) return

  parseFile(file).then(idsDirty => {
    idsClean = idsDirty.filter(id => id.trim().length > 0)
    buildDocument(idsClean)
  });
}

function parseFile(file) {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = function (e) {
      parsedLines = e.target.result.split(/\r|\n|\r\n/)
      resolve(parsedLines)
    }
    reader.readAsText(file)
  })
}

async function buildDocument(idsClean) {
  const releaseData = []
  for (const id of idsClean) {
    const data = await getRelease(id)
    releaseData.push(data)
  }
  const text = releaseData.join('\n')
  saveCsv(text, 'output')
}

;(async function accessInterval( ) {
  let accessInterval = 2400;
  if(idsClean !== undefined) {
    for ( const id of idsClean ) { // Wait until one has passed since the previous request was initiated
await new Promise( resolve => setTimeout( resolve, accessInterval ))
      try {
        lastRequest = new Date;
        const release = await getRelease( id );
      } catch ( err ) { // Handle request failure here,
        // Depending on the error, perhaps add another delay and retry
        // or loop up to some limit retrying on each iteration, increasing the delay each time you get a 429 error
        // At a minimum just log the skipped release id with console.log( id );
      } // end of catch
    } // end of for loop
  } // end of if statement
} )(); // end of async

function getRelease(id) {
  return fetch(`https://api.discogs.com/releases/${id}`,
    {
      headers: {
        'User-Agent': 'CSVforDiscogs/0.1',
      }
    })
    .then(response => response.json())
    .then(parseReleaseData)
  }

  function parseReleaseData(data) {
    if (data.message === 'Release not found.')
    return `Release with ID ${idFiltered} does not exist`

    const id = data.id
    const artists = data.artists ? data.artists.map(artist => artist.name) : []
    const title = data.title || []
    const format = data.formats[0].name || []
    const format_qty = data.formats[0].qty || []
    const format_descriptions = data.formats[0].descriptions || []
    const format_descriptions_formatted = format_descriptions.map(description => description.replace(/"/g, "\"\""))
    const label = data.labels[0].name || []
    const catno = data.labels[0].catno || []
    const identifiers = data.identifiers[0] || []
    const barcode = data.identifiers.filter((item) => item.type === 'Barcode')
    const barcode_values = barcode.map(barcode => barcode.value)
    const country = data.country || 'Unknown'
    const released = data.released_formatted || 'Unknown'
    const genres = data.genres || []
    const styles = data.styles || []
    const tracklist = data.tracklist ? data.tracklist.map(track => track.title) : []

    return [id, artists, title, label, catno, barcode_values, format, format_qty, '"' + format_descriptions_formatted + '"',
    country, released, '"' + genres + '"', '"' + styles + '"', '"' + tracklist + '"'].join(',')
  }

  function saveCsv(text, fileName) {
    const csvData = `data:text/csv;charset=utf-8,${text}`
    const encodedUri = encodeURI(csvData)
    const hiddenElement = document.createElement('a')
    hiddenElement.href = encodedUri
    hiddenElement.target = '_blank'
    hiddenElement.download = `${fileName}.csv`
    document.body.appendChild(hiddenElement)
    hiddenElement.click()
    hiddenElement.remove()
  }

它适用于最多15行的较小文件,但是当我尝试任何较大文件时,会出现类似this ...

的错误
  

获取https://api.discogs.com/releases/380504 429

     

访问CORS策略已阻止从源“空”获取“ https://api.discogs.com/releases/380504”处的访问:请求的资源上不存在“ Access-Control-Allow-Origin”标头。如果不透明的响应满足您的需求,请将请求的模式设置为“ no-cors”,以在禁用CORS的情况下获取资源。

     

未捕获(承诺)TypeError:无法获取

有人可以告诉我如何更好地控制它吗?

我正在访问的API的文档位于https://www.discogs.com/developers/

谢谢。

0 个答案:

没有答案