28 lines
968 B
JavaScript
28 lines
968 B
JavaScript
/**
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* Wait for some test to be true, returns a promise that resolves when condition is met.
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* Useful to wait for element render, for example. Uses requestAnimationFrame.
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*
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* @param {Function} testFn Test function to call. Should return true to resolve and false to continue testing.
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* @param {Number} maxTries Maximum number of rounds to test. If exceeded, the promise rejects. Defaults to 5000.
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* @return {Promise} Promise that resolves when test passes or rejects when maxTries is reached
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*/
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export const waitFor = (testFn, maxTries = 5000) => {
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return new Promise((resolve, reject) => {
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let tries = 0;
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const boundTestFn = testFn.bind(this);
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function waiter() {
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if (tries === maxTries) {
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return reject(new Error('waitFor: maximum tries exceeded'));
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}
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if (!boundTestFn()) {
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window.requestAnimationFrame(waiter);
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tries++;
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return;
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}
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resolve(true);
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}
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waiter();
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});
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} |