blobjs源码在这里为什么

Blob.js

/* Blob.js

/*global self, unescape */
/*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true,
plusplus: true */

/*! @source http://purl.eligrey.com/github/Blob.js/blob/master/Blob.js */

(function (view) {
"use strict";

view.URL = view.URL || view.webkitURL;

if (view.Blob && view.URL) {
    try {
        new Blob;
        return;
    } catch (e) {}
}

// Internally we use a BlobBuilder implementation to base Blob off of
// in order to support older browsers that only have BlobBuilder
var BlobBuilder = view.BlobBuilder || view.WebKitBlobBuilder || view.MozBlobBuilder || (function(view) {
    var
          get_class = function(object) {
            return Object.prototype.toString.call(object).match(/^\[object\s(.*)\]$/)[1];
        }
        , FakeBlobBuilder = function BlobBuilder() {
            this.data = [];
        }
        , FakeBlob = function Blob(data, type, encoding) {
            this.data = data;
            this.size = data.length;
            this.type = type;
            this.encoding = encoding;
        }
        , FBB_proto = FakeBlobBuilder.prototype
        , FB_proto = FakeBlob.prototype
        , FileReaderSync = view.FileReaderSync
        , FileException = function(type) {
            this.code = this[this.name = type];
        }
        , file_ex_codes = (
              "NOT_FOUND_ERR SECURITY_ERR ABORT_ERR NOT_READABLE_ERR ENCODING_ERR "
            + "NO_MODIFICATION_ALLOWED_ERR INVALID_STATE_ERR SYNTAX_ERR"
        ).split(" ")
        , file_ex_code = file_ex_codes.length
        , real_URL = view.URL || view.webkitURL || view
        , real_create_object_URL = real_URL.createObjectURL
        , real_revoke_object_URL = real_URL.revokeObjectURL
        , URL = real_URL
        , btoa = view.btoa
        , atob = view.atob

        , ArrayBuffer = view.ArrayBuffer
        , Uint8Array = view.Uint8Array

        , origin = /^[\w-]+:\/*\[?[\w\.:-]+\]?(?::[0-9]+)?/
    ;
    FakeBlob.fake = FB_proto.fake = true;
    while (file_ex_code--) {
        FileException.prototype[file_ex_codes[file_ex_code]] = file_ex_code + 1;
    }
    // Polyfill URL
    if (!real_URL.createObjectURL) {
        URL = view.URL = function(uri) {
            var
                  uri_info = document.createElementNS("http://www.w3.org/1999/xhtml", "a")
                , uri_origin
            ;
            uri_info.href = uri;
            if (!("origin" in uri_info)) {
                if (uri_info.protocol.toLowerCase() === "data:") {
                    uri_info.origin = null;
                } else {
                    uri_origin = uri.match(origin);
                    uri_info.origin = uri_origin && uri_origin[1];
                }
            }
            return uri_info;
        };
    }
    URL.createObjectURL = function(blob) {
        var
              type = blob.type
            , data_URI_header
        ;
        if (type === null) {
            type = "application/octet-stream";
        }
        if (blob instanceof FakeBlob) {
            data_URI_header = "data:" + type;
            if (blob.encoding === "base64") {
                return data_URI_header + ";base64," + blob.data;
            } else if (blob.encoding === "URI") {
                return data_URI_header + "," + decodeURIComponent(blob.data);
            } if (btoa) {
                return data_URI_header + ";base64," + btoa(blob.data);
            } else {
                return data_URI_header + "," + encodeURIComponent(blob.data);
            }
        } else if (real_create_object_URL) {
            return real_create_object_URL.call(real_URL, blob);
        }
    };
    URL.revokeObjectURL = function(object_URL) {
        if (object_URL.substring(0, 5) !== "data:" && real_revoke_object_URL) {
            real_revoke_object_URL.call(real_URL, object_URL);
        }
    };
    FBB_proto.append = function(data/*, endings*/) {
        var bb = this.data;
        // decode data to a binary string
        if (Uint8Array && (data instanceof ArrayBuffer || data instanceof Uint8Array)) {
            var
                  str = ""
                , buf = new Uint8Array(data)
                , i = 0
                , buf_len = buf.length
            ;
            for (; i < buf_len; i++) {
                str += String.fromCharCode(buf[i]);
            }
            bb.push(str);
        } else if (get_class(data) === "Blob" || get_class(data) === "File") {
            if (FileReaderSync) {
                var fr = new FileReaderSync;
                bb.push(fr.readAsBinaryString(data));
            } else {
                // async FileReader won't work as BlobBuilder is sync
                throw new FileException("NOT_READABLE_ERR");
            }
        } else if (data instanceof FakeBlob) {
            if (data.encoding === "base64" && atob) {
                bb.push(atob(data.data));
            } else if (data.encoding === "URI") {
                bb.push(decodeURIComponent(data.data));
            } else if (data.encoding === "raw") {
                bb.push(data.data);
            }
        } else {
            if (typeof data !== "string") {
                data += ""; // convert unsupported types to strings
            }
            // decode UTF-16 to binary string
            bb.push(unescape(encodeURIComponent(data)));
        }
    };
    FBB_proto.getBlob = function(type) {
        if (!arguments.length) {
            type = null;
        }
        return new FakeBlob(this.data.join(""), type, "raw");
    };
    FBB_proto.toString = function() {
        return "[object BlobBuilder]";
    };
    FB_proto.slice = function(start, end, type) {
        var args = arguments.length;
        if (args < 3) {
            type = null;
        }
        return new FakeBlob(
              this.data.slice(start, args > 1 ? end : this.data.length)
            , type
            , this.encoding
        );
    };
    FB_proto.toString = function() {
        return "[object Blob]";
    };
    FB_proto.close = function() {
        this.size = 0;
        delete this.data;
    };
    return FakeBlobBuilder;
}(view));

view.Blob = function(blobParts, options) {
    var type = options ? (options.type || "") : "";
    var builder = new BlobBuilder();
    if (blobParts) {
        for (var i = 0, len = blobParts.length; i < len; i++) {
            if (Uint8Array && blobParts[i] instanceof Uint8Array) {
                builder.append(blobParts[i].buffer);
            }
            else {
                builder.append(blobParts[i]);
            }
        }
    }
    var blob = builder.getBlob(type);
    if (!blob.slice && blob.webkitSlice) {
        blob.slice = blob.webkitSlice;
    }
    return blob;
};

var getPrototypeOf = Object.getPrototypeOf || function(object) {
    return object.__proto__;
};
view.Blob.prototype = getPrototypeOf(new view.Blob());

}(typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content || this));

Csdn user default icon
上传中...
上传图片
插入图片
抄袭、复制答案,以达到刷声望分或其他目的的行为,在CSDN问答是严格禁止的,一经发现立刻封号。是时候展现真正的技术了!
立即提问
相关内容推荐