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Don't mix formal parameters and arguments array #462

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Don't mix formal parameters and arguments array #462

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3 changes: 2 additions & 1 deletion es6-shim.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1387,7 +1387,8 @@
var isBadHex = isBadHexRegex.test.bind(isBadHexRegex);
var NumberShim = (function () {
// this is wrapped in an IIFE because of IE 6-8's wacky scoping issues with named function expressions.
var NumberShim = function Number(value) {
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@ljharb ljharb Feb 28, 2020

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this would be a breaking change; Number.length must be 1.

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@milk-z milk-z Feb 28, 2020

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I missed that requirement! Thanks.
I will need to think about this some more then, just by having the formal parameter, even if only arguments is used, IE11 is much slower than only having formal parameters or only having arguments.

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@ljharb ljharb Feb 28, 2020

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Unfortunately function lengths are not configurable in IE 11, so the only way to get a length of 1 is to have a formal parameter.

var NumberShim = function Number() {
var value = arguments[0];
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@ljharb ljharb Feb 28, 2020

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but i'm fine using the value out of the arguments object - however, if arguments.length < 1, arguments[0] deoptimizes in many engines, including older v8.

var primValue;
if (arguments.length > 0) {
primValue = Type.primitive(value) ? value : toPrimitive(value, 'number');
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