JSFiddle - React, Tailwind, and code Playground

JavaScript

var json = {
    json: JSON.stringify({
        a: 1,
        b: 2
    }),
    delay: 1
};

fetch('/echo/json/', {
    method: 'post',
    headers: {
        'Accept': 'application/json, text/plain, */*',
        'Content-Type': 'application/json'
    },
    body: 'json=' + encodeURI(JSON.stringify(json.json)) + '&delay=' + json.delay
})
    .then(function (response) {
    return response.json();
})
    .then(function (result) {
    alert(JSON.stringify(result));
})
    .
catch (function (error) {
    console.log('Request failed', error);
});