57 lines
1.7 KiB
JavaScript
57 lines
1.7 KiB
JavaScript
/*
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* SystemJS global script loading support
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* Extra for the s.js build only
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* (Included by default in system.js build)
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*/
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(function (global) {
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const systemJSPrototype = System.constructor.prototype;
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function getLastGlobalProp () {
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// alternatively Object.keys(global).pop()
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// but this may be faster (pending benchmarks)
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let lastProp;
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for (let p in global)
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if (global.hasOwnProperty(p))
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lastProp = p;
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return lastProp;
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}
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let lastGlobalProp;
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const impt = systemJSPrototype.import;
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systemJSPrototype.import = function (id, parentUrl) {
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lastGlobalProp = getLastGlobalProp();
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return impt.call(this, id, parentUrl);
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};
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const emptyInstantiation = [[], function () { return {} }];
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const getRegister = systemJSPrototype.getRegister;
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systemJSPrototype.getRegister = function () {
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const lastRegister = getRegister.call(this);
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if (lastRegister)
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return lastRegister;
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// no registration -> attempt a global detection as difference from snapshot
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// when multiple globals, we take the global value to be the last defined new global object property
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// for performance, this will not support multi-version / global collisions as previous SystemJS versions did
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// note in Edge, deleting and re-adding a global does not change its ordering
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const globalProp = getLastGlobalProp();
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if (lastGlobalProp === globalProp)
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return emptyInstantiation;
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lastGlobalProp = globalProp;
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let globalExport;
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try {
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globalExport = global[globalProp];
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}
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catch (e) {
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return emptyInstantiation;
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}
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return [[], function (_export) {
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return { execute: function () { _export('default', globalExport) } };
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}];
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};
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})(typeof self !== 'undefined' ? self : global); |