mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-18 05:19:29 +08:00
Chris Tate
94fd361b54
Represent ordinary JavaScript arrays with hole, value, and explicit-undefined states; add sparse side storage and carry missing values through the frontend, native backends, runtime, and Node-facing consumers.
23 lines
831 B
TypeScript
23 lines
831 B
TypeScript
// Numeric consumers use JavaScript's ToNumber(undefined) = NaN while
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// strict equality keeps the original undefined union arm. A wider array
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// element union may use number operations after a typeof guard without
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// losing that runtime-optional representation.
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const numbers: number[] = [5];
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console.log(numbers[4] < 10, numbers[4] <= 10, numbers[4] > 10, numbers[4] >= 10);
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console.log(numbers[4] === numbers[4]);
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const missing: number | undefined = numbers[4];
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console.log(missing === undefined, missing !== undefined);
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let indexCalls = 0;
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function missingIndex(): number {
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indexCalls++;
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return 4;
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}
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console.log(numbers[missingIndex()] < 10, indexCalls);
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const mixed: (string | number)[] = ["first", 20];
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const second = mixed[1];
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if (typeof second === "number") {
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console.log(second + 1, second < 30, second === 20);
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}
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