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April 18, 2018 11:41
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Wait until condition is truthy and only then - proceed
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| /** | |
| * 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)); |
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