JSON.parse() 与..json()

2022-01-20 00:00:00 json fetch javascript

我最近一直在使用 fetch API 和 Promises，我遇到了 .json() ..json() 通常返回与 JSON.parse 相同的输出.我用谷歌搜索了这个问题，结果指向了其他方向.

I have been working with fetch API and Promises recently and I came across .json() . Oftentimes .json() returns the same output as JSON.parse. I googled the question and the results pointed in other directions.

XHR 和 JSON.parse 示例:

Example with XHR and JSON.parse:

$('#xhr').click(function(){
  var XHR = new XMLHttpRequest();

  XHR.onreadystatechange = function(){
    if (XHR.status == 200 && XHR.readyState == 4) {
      $('#quote').text(JSON.parse(XHR.responseText)[0]);
    }
  };

  XHR.open("GET", url);
  XHR.send();
});

Fetch API 示例:

Example with Fetch API:

$('#fetch').click(function(){
  fetch(url)
  .then(function(res){
    return res.json();
  })
  .then(function(quote){
    $('#quote').text(quote);
  })
  .catch(function(err){
    handleError(err);
  });
});

有人能解释一下这些看似相似的概念之间的区别吗?谢谢

Could someone please explain the difference between these seemingly similar concepts ? Thanks

推荐答案

Body.json() 是异步的，并返回一个解析为 JavaScript 对象的 Promise 对象.JSON.parse() 是同步的，可以解析一个字符串并改变结果返回的 JavaScript 对象.

Body.json() is asynchronous and returns a Promise object that resolves to a JavaScript object. JSON.parse() is synchronous can parse a string and change the resulting returned JavaScript object.

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