vue hello world项目
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3 years ago
var anObject = require('../internals/an-object');
var aConstructor = require('../internals/a-constructor');
var wellKnownSymbol = require('../internals/well-known-symbol');
var SPECIES = wellKnownSymbol('species');
// `SpeciesConstructor` abstract operation
// https://tc39.es/ecma262/#sec-speciesconstructor
module.exports = function (O, defaultConstructor) {
var C = anObject(O).constructor;
var S;
return C === undefined || (S = anObject(C)[SPECIES]) == undefined ? defaultConstructor : aConstructor(S);
};