Wait until condition is truthy and only then - proceed

wait-until.js

/**
 * Example of an async function which returns some value
 */
function doSomething() {
  return new Promise((resolve, reject) => {
    window.setTimeout(function () {
      resolve(Math.random() > 0.8);
    }, 1000);
  });
}

/**
 * Checks whether a condition applies, in order to tell waitUntil to proceed
 * @param {object} data - The response from the business function above
 */
function evaluate(data) {
  return data === true;
}

/**
 * Waits for a condition to be truthy and proceed
 */
async function waitUntil(extract, evaluate, max) {
  let data;
  let truthy;
  let counter = 0;
  
  while ((!max||counter < max) && !truthy) {
    data = await extract();
    truthy = evaluate(data);
    counter++
  };
  
  return data;
}

// how to use:
waitUntil(doSomething, evaluate)
  .then(isTrue => console.log(isTrue));
  
// how to use - try 3 times maximum:
waitUntil(doSomething, evaluate, 3)
  .then(isTrue => console.log(isTrue));