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use Symbol.hasInstance #46

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Merged
merged 2 commits into from
Jun 11, 2020
Merged

use Symbol.hasInstance #46

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1695506
refactor isBlob into symbol
tinovyatkin Jun 11, 2020
f9d6548
lint
tinovyatkin Jun 11, 2020
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39 changes: 16 additions & 23 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -15,20 +15,6 @@ async function * read(parts) {
}
}

/**
* @template T
* @param {T} object
* @returns {T is Blob}
*/
const isBlob = object => {
return (
typeof object === 'object' &&
typeof object.stream === 'function' &&
typeof object.constructor === 'function' &&
/^(Blob|File)$/.test(object[Symbol.toStringTag])
);
};

class Blob {
/**
* The Blob() constructor returns a new Blob object. The content
Expand All @@ -43,13 +29,13 @@ class Blob {

const parts = blobParts.map(element => {
let buffer;
if (Buffer.isBuffer(element)) {
if (element instanceof Buffer) {
buffer = element;
} else if (ArrayBuffer.isView(element)) {
buffer = Buffer.from(element.buffer, element.byteOffset, element.byteLength);
} else if (element instanceof ArrayBuffer) {
buffer = Buffer.from(element);
} else if (isBlob(element)) {
} else if (element instanceof Blob) {
buffer = element;
} else {
buffer = Buffer.from(typeof element === 'string' ? element : String(element));
Expand Down Expand Up @@ -167,6 +153,20 @@ class Blob {

return blob;
}

get [Symbol.toStringTag]() {
return 'Blob';
}

static [Symbol.hasInstance](object) {
return (
typeof object === 'object' &&
typeof object.stream === 'function' &&
object.stream.length === 0 &&
typeof object.constructor === 'function' &&
/^(Blob|File)$/.test(object[Symbol.toStringTag])
);
}
}

Object.defineProperties(Blob.prototype, {
Expand All @@ -175,11 +175,4 @@ Object.defineProperties(Blob.prototype, {
slice: {enumerable: true}
});

Object.defineProperty(Blob.prototype, Symbol.toStringTag, {
value: 'Blob',
writable: false,
enumerable: false,
configurable: true
});

module.exports = Blob;