systemjs · guybedford · Jul 23, 2020 · Feb 28, 2020 · Jul 23, 2020 · Jul 23, 2020
diff --git a/src/common.js b/src/common.js
@@ -152,7 +152,7 @@ function resolveAndComposePackages (packages, outPackages, baseUrl, parentMap, p
 }
 
 export function resolveAndComposeImportMap (json, baseUrl, parentMap) {
-  var outMap = { imports: objectAssign({}, parentMap.imports), scopes: objectAssign({}, parentMap.scopes) };
+  var outMap = { imports: objectAssign({}, parentMap.imports), scopes: objectAssign({}, parentMap.scopes), depcache: objectAssign({}, parentMap.depcache) };
 
   if (json.imports)
     resolveAndComposePackages(json.imports, outMap.imports, baseUrl, parentMap, null);
@@ -163,6 +163,12 @@ export function resolveAndComposeImportMap (json, baseUrl, parentMap) {
       resolveAndComposePackages(json.scopes[s], outMap.scopes[resolvedScope] || (outMap.scopes[resolvedScope] = {}), baseUrl, parentMap, resolvedScope);
     }
 
+  if (json.depcache)
+    for (var d in json.depcache) {
+      var resolvedDepcache = resolveUrl(d, baseUrl);
+      outMap.depcache[resolvedDepcache] = json.depcache[d];
+    }
+
   return outMap;
 }
 

diff --git a/src/features/browser-scripts.js → src/features/import-maps.js b/src/features/browser-scripts.js → src/features/import-maps.js
@@ -2,10 +2,10 @@
  * SystemJS browser attachments for script and import map processing
  */
 import { baseUrl, resolveAndComposeImportMap, hasDocument, resolveUrl, IMPORT_MAP } from '../common.js';
-import { systemJSPrototype } from '../system-core.js';
+import { systemJSPrototype, getOrCreateLoad } from '../system-core.js';
 import { errMsg } from '../err-msg.js';
 
-var importMapPromise = Promise.resolve({ imports: {}, scopes: {} });
+var importMapPromise = Promise.resolve({ imports: {}, scopes: {}, depcache: {} });
 
 // Scripts are processed immediately, on the first System.import, and on DOMReady.
 // Import map scripts are processed only once (by being marked) and in order for each phase.
@@ -26,6 +26,16 @@ if (hasDocument) {
   window.addEventListener('DOMContentLoaded', processScripts);
 }
 
+const systemInstantiate = systemJSPrototype.instantiate;
+systemJSPrototype.instantiate = function (url, firstParentUrl) {
+  var preloads = this[IMPORT_MAP].depcache[url];
+  if (preloads) {
+    for (var i = 0; i < preloads.length; i++)
+      getOrCreateLoad(this, this.resolve(preloads[i], url), url);
+  }
+  return systemInstantiate.call(this, url, firstParentUrl);
+};
+
 function processScripts () {
   [].forEach.call(document.querySelectorAll('script'), function (script) {
     if (script.sp) // sp marker = systemjs processed

diff --git a/src/s.js b/src/s.js
@@ -1,5 +1,5 @@
-import './features/resolve.js';
-import './features/browser-scripts.js';
 import './features/script-load.js';
+import './features/resolve.js';
+import './features/import-maps.js';
 import './features/auto-import.js';
 import './features/worker-load.js';
diff --git a/src/system-core.js b/src/system-core.js
@@ -72,7 +72,7 @@ systemJSPrototype.getRegister = function () {
   return _lastRegister;
 };
 
-function getOrCreateLoad (loader, id, firstParentUrl) {
+export function getOrCreateLoad (loader, id, firstParentUrl) {
   var load = loader[REGISTRY][id];
   if (load)
     return load;

diff --git a/src/system.js b/src/system.js
@@ -1,6 +1,6 @@
-import './features/resolve.js';
-import './features/browser-scripts.js';
 import './features/script-load.js';
+import './features/resolve.js';
+import './features/import-maps.js';
 import './features/auto-import.js';
 import './features/worker-load.js';
 import './extras/global.js';

diff --git a/test/browser/core.js b/test/browser/core.js
@@ -226,6 +226,13 @@ suite('SystemJS Standard Tests', function() {
     });
   });
 
+  test('should support depcache', function () {
+    return System.import('/test/fixtures/browser/depcache.js').then(function (m) {
+      assert.ok(m);
+      assert.equal(m.default, '10th module');
+    });
+  });
+
   test('should not get confused by filenames in url hash when resolving module type', function () {
     return System.import('fixturesbase/css-modules/hash.css?foo=bar.html').then(function (m) {
       assert.ok(m);

diff --git a/test/fixtures/browser/depcache.js b/test/fixtures/browser/depcache.js
@@ -0,0 +1,9 @@
+System.register(['./depcache1.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache1.js b/test/fixtures/browser/depcache1.js
@@ -0,0 +1,9 @@
+System.register(['./depcache2.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache10.js b/test/fixtures/browser/depcache10.js
@@ -0,0 +1,7 @@
+System.register([], function(_export) {
+  return {
+    execute: function () {
+      _export('default', '10th module');
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache2.js b/test/fixtures/browser/depcache2.js
@@ -0,0 +1,9 @@
+System.register(['./depcache3.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache3.js b/test/fixtures/browser/depcache3.js
@@ -0,0 +1,9 @@
+System.register(['./depcache4.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache4.js b/test/fixtures/browser/depcache4.js
@@ -0,0 +1,9 @@
+System.register(['./depcache5.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache5.js b/test/fixtures/browser/depcache5.js
@@ -0,0 +1,9 @@
+System.register(['./depcache6.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache6.js b/test/fixtures/browser/depcache6.js
@@ -0,0 +1,9 @@
+System.register(['./depcache7.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache7.js b/test/fixtures/browser/depcache7.js
@@ -0,0 +1,9 @@
+System.register(['./depcache8.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache8.js b/test/fixtures/browser/depcache8.js
@@ -0,0 +1,9 @@
+System.register(['./depcache9.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/depcache9.js b/test/fixtures/browser/depcache9.js
@@ -0,0 +1,9 @@
+System.register(['./depcache10.js'], function(_export) {
+  var dep;
+  return {
+    setters: [function (_dep) { dep = _dep.default }],
+    execute: function () {
+      _export('default', dep);
+    }
+  };
+});
diff --git a/test/fixtures/browser/importmap.json b/test/fixtures/browser/importmap.json
@@ -19,5 +19,17 @@
     "wasm/": {
       "example": "./wasm/example.js"
     }
+  },
+  "depcache": {
+    "depcache.js": ["./depcache1.js"],
+    "depcache1.js": ["./depcache2.js"],
+    "depcache2.js": ["./depcache3.js"],
+    "depcache3.js": ["./depcache4.js"],
+    "depcache4.js": ["./depcache5.js"],
+    "depcache5.js": ["./depcache6.js"],
+    "depcache6.js": ["./depcache7.js"],
+    "depcache7.js": ["./depcache8.js"],
+    "depcache8.js": ["./depcache9.js"],
+    "depcache9.js": ["./depcache10.js"]
   }
 }