你可以使用FormData和URLSearchParams发布为application/x-www-form-urlencoded，示例如下:

如果你有一个表格:

<form>
    <input name="username" type="text" />
    <input name="password" type="password" />
    <button type="submit">login</button>
</form>

您可以添加使用下面的JS来提交表单。

const form = document.querySelector("form");

form.addEventListener("submit", async () => {
    const formData = new FormData(form);
    try {
        await fetch("https://example.com/login", {
            method: "POST",
            headers: {
                "Content-Type": "application/x-www-form-urlencoded",
            },
            body: new URLSearchParams(formData),
        });
    } catch (err) {
        console.log(err);
    }
});

使用URLSearchParams

https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams

var data = new URLSearchParams();
data.append('userName', 'test@gmail.com');
data.append('password', 'Password');
data.append('grant_type', 'password');

你必须自己把x-www-form-urlencoded有效负载放在一起，就像这样:

var details = {
    'userName': 'test@gmail.com',
    'password': 'Password!',
    'grant_type': 'password'
};

var formBody = [];
for (var property in details) {
  var encodedKey = encodeURIComponent(property);
  var encodedValue = encodeURIComponent(details[property]);
  formBody.push(encodedKey + "=" + encodedValue);
}
formBody = formBody.join("&");

fetch('https://example.com/login', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8'
  },
  body: formBody
})

注意，如果你在一个(足够现代的)浏览器中使用fetch，而不是React Native，你可以创建一个URLSearchParams对象并使用它作为主体，因为fetch标准声明，如果主体是一个URLSearchParams对象，那么它应该被序列化为application/x-www-form-urlencoded。然而，你不能在React Native中这样做，因为React Native没有实现URLSearchParams。

不需要使用jQuery、querystring或手动组装有效负载。URLSearchParams是一种方法，这里是一个最简洁的答案与完整的请求示例:

fetch('https://example.com/login', {
  method: 'POST',
  body: new URLSearchParams({
    param: 'Some value',
    anotherParam: 'Another value'
  })
})
  .then(response => {
    // Do stuff with the response
  });

同样的技术使用async / await。

const login = async () => {
  const response = await fetch('https://example.com/login', {
    method: 'POST',
    body: new URLSearchParams({
      param: 'Some value',
      anotherParam: 'Another value'
    })
  })

  // Do stuff with the response
}

是的，您可以使用Axios或任何其他HTTP客户端库来代替本机获取。

只使用

import  qs from "qs";
 let data = {
        'profileId': this.props.screenProps[0],
        'accountId': this.props.screenProps[1],
        'accessToken': this.props.screenProps[2],
        'itemId': this.itemId
    };
    return axios.post(METHOD_WALL_GET, qs.stringify(data))

根据规范，使用encodeURIComponent不会给你一个符合要求的查询字符串。州:

Control names and values are escaped. Space characters are replaced by +, and then reserved characters are escaped as described in [RFC1738], section 2.2: Non-alphanumeric characters are replaced by %HH, a percent sign and two hexadecimal digits representing the ASCII code of the character. Line breaks are represented as "CR LF" pairs (i.e., %0D%0A). The control names/values are listed in the order they appear in the document. The name is separated from the value by = and name/value pairs are separated from each other by &.

问题是，encodeURIComponent将空格编码为%20，而不是+。

表单主体应该使用其他答案中显示的encodeURIComponent方法的变体进行编码。

const formUrlEncode = str => {
  return str.replace(/[^\d\w]/g, char => {
    return char === " " 
      ? "+" 
      : encodeURIComponent(char);
  })
}

const data = {foo: "bar߃©˙∑  baz", boom: "pow"};

const dataPairs = Object.keys(data).map( key => {
  const val = data[key];
  return (formUrlEncode(key) + "=" + formUrlEncode(val));
}).join("&");

// dataPairs is "foo=bar%C3%9F%C6%92%C2%A9%CB%99%E2%88%91++baz&boom=pow"