mirror of https://github.com/jkjoy/sunpeiwen.git
74 lines
2.4 KiB
JavaScript
74 lines
2.4 KiB
JavaScript
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exports.fetch = isFunction(global.fetch) && isFunction(global.ReadableStream)
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exports.writableStream = isFunction(global.WritableStream)
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exports.abortController = isFunction(global.AbortController)
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exports.blobConstructor = false
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try {
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new Blob([new ArrayBuffer(1)])
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exports.blobConstructor = true
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} catch (e) {}
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// The xhr request to example.com may violate some restrictive CSP configurations,
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// so if we're running in a browser that supports `fetch`, avoid calling getXHR()
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// and assume support for certain features below.
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var xhr
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function getXHR () {
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// Cache the xhr value
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if (xhr !== undefined) return xhr
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if (global.XMLHttpRequest) {
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xhr = new global.XMLHttpRequest()
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// If XDomainRequest is available (ie only, where xhr might not work
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// cross domain), use the page location. Otherwise use example.com
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// Note: this doesn't actually make an http request.
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try {
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xhr.open('GET', global.XDomainRequest ? '/' : 'https://example.com')
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} catch(e) {
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xhr = null
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}
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} else {
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// Service workers don't have XHR
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xhr = null
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}
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return xhr
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}
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function checkTypeSupport (type) {
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var xhr = getXHR()
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if (!xhr) return false
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try {
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xhr.responseType = type
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return xhr.responseType === type
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} catch (e) {}
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return false
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}
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// For some strange reason, Safari 7.0 reports typeof global.ArrayBuffer === 'object'.
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// Safari 7.1 appears to have fixed this bug.
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var haveArrayBuffer = typeof global.ArrayBuffer !== 'undefined'
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var haveSlice = haveArrayBuffer && isFunction(global.ArrayBuffer.prototype.slice)
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// If fetch is supported, then arraybuffer will be supported too. Skip calling
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// checkTypeSupport(), since that calls getXHR().
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exports.arraybuffer = exports.fetch || (haveArrayBuffer && checkTypeSupport('arraybuffer'))
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// These next two tests unavoidably show warnings in Chrome. Since fetch will always
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// be used if it's available, just return false for these to avoid the warnings.
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exports.msstream = !exports.fetch && haveSlice && checkTypeSupport('ms-stream')
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exports.mozchunkedarraybuffer = !exports.fetch && haveArrayBuffer &&
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checkTypeSupport('moz-chunked-arraybuffer')
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// If fetch is supported, then overrideMimeType will be supported too. Skip calling
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// getXHR().
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exports.overrideMimeType = exports.fetch || (getXHR() ? isFunction(getXHR().overrideMimeType) : false)
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exports.vbArray = isFunction(global.VBArray)
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function isFunction (value) {
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return typeof value === 'function'
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}
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xhr = null // Help gc
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