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Response: json() method

files/en-us/web/api/response/json/index.md

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{{APIRef("Fetch API")}}{{AvailableInWorkers}}

The json() method of the {{DOMxRef("Response")}} interface takes a {{DOMxRef("Response")}} stream and reads it to completion. It returns a promise which resolves with the result of parsing the body text as {{JSxRef("JSON")}}.

Note that despite the method being named json(), the result is not JSON but is instead the result of taking JSON as input and parsing it to produce a JavaScript object.

Syntax

js-nolint
json()

Parameters

None.

Return value

A {{jsxref("Promise")}} that resolves to a JavaScript object. This object could be anything that can be represented by JSON — an object, an array, a string, a number…

Exceptions

  • AbortError {{domxref("DOMException")}}
  • {{jsxref("TypeError")}}
    • : Thrown for one of the following reasons:
      • The response body is disturbed or locked.
      • There was an error decoding the body content (for example, because the {{httpheader("Content-Encoding")}} header is incorrect).
  • {{jsxref("SyntaxError")}}
    • : The response body cannot be parsed as JSON.

Examples

In our fetch JSON example (run fetch JSON live), we create a new request using the {{DOMxRef("Request.Request", "Request()")}} constructor, then use it to fetch a .json file. When the fetch is successful, we read and parse the data using json(), then read values out of the resulting objects as you'd expect and insert them into list items to display our product data.

js
const myList = document.querySelector("ul");
const myRequest = new Request("products.json");

fetch(myRequest)
  .then((response) => response.json())
  .then((data) => {
    for (const product of data.products) {
      const listItem = document.createElement("li");
      listItem.appendChild(document.createElement("strong")).textContent =
        product.Name;
      listItem.append(` can be found in ${product.Location}. Cost: `);
      listItem.appendChild(document.createElement("strong")).textContent =
        `£${product.Price}`;
      myList.appendChild(listItem);
    }
  })
  .catch(console.error);

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also