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eamonnboyle/AssertionFunctions.ts

Created August 27, 2021 10:09
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Assertion Functions
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AssertionFunctions.ts
function assertIsTextArea(input: HTMLInputElement | HTMLTextAreaElement): asserts input is HTMLTextAreaElement {
if (!('rows' in input)) {
throw new Error("Expected a HTMLTextAreaElement");
}
}
assertIsTextArea(input);
// If we get to this line, no exception has been thrown
// Therefore, input has type HTMLTextAreaElement
input.rows = 25;
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