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Chris Tate
3195f98401
A const initialized by an array literal and spread once can still run that spread more than once: in a loop body, loop test or update, a function, or a class field initializer. Each run inserts the same elements in JavaScript, so copying them into the destination's layout would break identity. Those spreads keep the element-layout refusal.
17 lines
791 B
TypeScript
17 lines
791 B
TypeScript
// A const array spread that runs more than once per evaluation of its
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// initializer inserts the same elements each time: in a loop body or in a
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// function, `results[1] === results[2]` holds in Node. Converting the
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// elements into the destination's layout would copy them on each run, so
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// these spreads keep the element-layout refusal.
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type Result = { message: string; file: { path: string } | undefined; noisy: boolean };
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const results: Result[] = [];
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const looped = [{ message: "loop", file: undefined, noisy: false }];
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for (let i = 0; i < 2; i++) results.push(...looped);
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const called = [{ message: "call", file: undefined, noisy: true }];
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function addCalled(): void {
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results.unshift(...called);
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}
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addCalled();
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addCalled();
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console.log(results.length, results[0] === results[1]);
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