JSFiddle - React, Tailwind, and code Playground

JavaScript

var json = { 
    json: JSON.stringify({
        a: 1, 
        b: 2
    }),
    delay: 5
};

fetch('/echo/json/', {  
    method: 'post',  
    headers: {
      'Accept': 'application/json',
      'Content-Type': 'application/json'
    },
    body: json
  })
  .then(function (data) {  
    console.log('Request succeeded with JSON response', data);  
  })  
  .catch(function (error) {  
    console.log('Request failed', error);  
  });