fix "dependency is an expression" issue

README.md

@@ -122,13 +122,33 @@ doc.save("a4.pdf");
 ### Optional dependencies
 
 Some functions of jsPDF require optional dependencies. E.g. the `html` method, which depends on `html2canvas` and,
-when supplied with a string HTML document, `dompurify`. You need to install them explicitly, e.g.:
+when supplied with a string HTML document, `dompurify`. JsPDF loads them dynamically when required
+(using the respective module format, e.g. dynamic imports). Build tools like Webpack will automatically create separate
+chunks for each of the optional dependencies. If your application does not use any of the optional dependencies, you
+can prevent Webpack from generating the chunks by defining them as external dependencies:
 
-```sh
-npm install --save html2canvas dompurify
+```js
+// webpack.config.js
+module.exports = {
+  // ...
+  externals: {
+    // only define the dependencies you are NOT using as externals!
+    canvg: "canvg",
+    html2canvas: "html2canvas",
+    dompurify: "dompurify"
+  }
+};
 ```
 
-jsPDF will then dynamically load them when required (using the respective module format, e.g. dynamic imports).
+In **Vue CLI** projects, externals can be defined via the [configureWebpack](https://cli.vuejs.org/config/#configurewebpack)
+or [chainWebpack](https://cli.vuejs.org/config/#chainwebpack) properties of the `vue.config.js` file
+(needs to be created, first, in fresh projects).
+
+In **Angular** projects, externals can be defined using
+[custom webpack builders](https://github.com/just-jeb/angular-builders/tree/master/packages/custom-webpack).
+
+In **React** (`create-react-app`) projects, externals can be defined by either using
+[react-app-rewired](https://github.com/timarney/react-app-rewired) or ejecting.
 
 ### TypeScript/Angular/Webpack/React/etc. Configuration:
 

package.json

@@ -5,7 +5,6 @@
   "description": "PDF Document creation from JavaScript",
   "main": "dist/jspdf.node.min.js",
   "module": "dist/jspdf.es.min.js",
-  "browser": "dist/jspdf.umd.min.js",
   "files": [
     "dist",
     "types/index.d.ts",

rollup.config.js

@@ -38,10 +38,8 @@ const umdExternals = matchSubmodules([
 ]);
 const externals = matchSubmodules([
   ...Object.keys(pkg.dependencies || {}),
-  ...[
-    ...Object.keys(pkg.peerDependencies || {}),
-    ...Object.keys(pkg.optionalDependencies || {})
-  ]
+  ...Object.keys(pkg.peerDependencies || {}),
+  ...Object.keys(pkg.optionalDependencies || {})
 ]);
 
 const umd = {
@@ -162,7 +160,7 @@ const esPolyfills = {
 };
 
 function matchSubmodules(externals) {
-  return externals.map(e => new RegExp(`^${e}[/\\\\]`));
+  return externals.map(e => new RegExp(`^${e}(?:[/\\\\]|$)`));
 }
 
 export default [umd, es, node, umdPolyfills, esPolyfills];

src/modules/html.js

@@ -8,7 +8,7 @@
  */
 
 import { jsPDF } from "../jspdf.js";
-import { loadOptionalLibrary } from "../libs/loadOptionalLibrary.js";
+import { globalObject } from "../libs/globalObject.js";
 
 /**
  * jsPDF html PlugIn
@@ -20,15 +20,83 @@ import { loadOptionalLibrary } from "../libs/loadOptionalLibrary.js";
   "use strict";
 
   function loadHtml2Canvas() {
-    return loadOptionalLibrary("html2canvas").catch(function(e) {
-      return Promise.reject(new Error("Could not load html2canvas: " + e));
-    });
+    return (function() {
+      if (globalObject["html2canvas"]) {
+        return Promise.resolve(globalObject["html2canvas"]);
+      }
+
+      // @if MODULE_FORMAT='es'
+      return import("html2canvas");
+      // @endif
+
+      // @if MODULE_FORMAT!='es'
+      if (typeof exports === "object" && typeof module !== "undefined") {
+        return new Promise(function(resolve, reject) {
+          try {
+            resolve(require("html2canvas"));
+          } catch (e) {
+            reject(e);
+          }
+        });
+      }
+      if (typeof define === "function" && define.amd) {
+        return new Promise(function(resolve, reject) {
+          try {
+            require(["html2canvas"], resolve);
+          } catch (e) {
+            reject(e);
+          }
+        });
+      }
+      return Promise.reject(new Error("Could not load " + name));
+      // @endif
+    })()
+      .catch(function(e) {
+        return Promise.reject(new Error("Could not load dompurify: " + e));
+      })
+      .then(function(html2canvas) {
+        return html2canvas.default ? html2canvas.default : html2canvas;
+      });
   }
 
   function loadDomPurify() {
-    return loadOptionalLibrary("dompurify", "DOMPurify").catch(function(e) {
-      return Promise.reject(new Error("Could not load dompurify: " + e));
-    });
+    return (function() {
+      if (globalObject["DOMPurify"]) {
+        return Promise.resolve(globalObject["DOMPurify"]);
+      }
+
+      // @if MODULE_FORMAT='es'
+      return import("dompurify");
+      // @endif
+
+      // @if MODULE_FORMAT!='es'
+      if (typeof exports === "object" && typeof module !== "undefined") {
+        return new Promise(function(resolve, reject) {
+          try {
+            resolve(require("dompurify"));
+          } catch (e) {
+            reject(e);
+          }
+        });
+      }
+      if (typeof define === "function" && define.amd) {
+        return new Promise(function(resolve, reject) {
+          try {
+            require(["dompurify"], resolve);
+          } catch (e) {
+            reject(e);
+          }
+        });
+      }
+      return Promise.reject(new Error("Could not load " + name));
+      // @endif
+    })()
+      .catch(function(e) {
+        return Promise.reject(new Error("Could not load dompurify: " + e));
+      })
+      .then(function(dompurify) {
+        return dompurify.default ? dompurify.default : dompurify;
+      });
   }
 
   /**

src/modules/svg.js

@@ -23,8 +23,8 @@
  */
 
 import { jsPDF } from "../jspdf.js";
-import { loadOptionalLibrary } from "../libs/loadOptionalLibrary.js";
 import { console } from "../libs/console.js";
+import { globalObject } from "../libs/globalObject.js";
 
 /**
  * jsPDF SVG plugin
@@ -35,6 +35,46 @@ import { console } from "../libs/console.js";
 (function(jsPDFAPI) {
   "use strict";
 
+  function loadCanvg() {
+    return (function() {
+      if (globalObject["canvg"]) {
+        return Promise.resolve(globalObject["canvg"]);
+      }
+
+      // @if MODULE_FORMAT='es'
+      return import("canvg");
+      // @endif
+
+      // @if MODULE_FORMAT!='es'
+      if (typeof exports === "object" && typeof module !== "undefined") {
+        return new Promise(function(resolve, reject) {
+          try {
+            resolve(require("canvg"));
+          } catch (e) {
+            reject(e);
+          }
+        });
+      }
+      if (typeof define === "function" && define.amd) {
+        return new Promise(function(resolve, reject) {
+          try {
+            require(["canvg"], resolve);
+          } catch (e) {
+            reject(e);
+          }
+        });
+      }
+      return Promise.reject(new Error("Could not load " + name));
+      // @endif
+    })()
+      .catch(function(e) {
+        return Promise.reject(new Error("Could not load dompurify: " + e));
+      })
+      .then(function(canvg) {
+        return canvg.default ? canvg.default : canvg;
+      });
+  }
+
   /**
    * Parses SVG XML and saves it as image into the PDF.
    *
@@ -89,7 +129,7 @@ import { console } from "../libs/console.js";
       ignoreDimensions: true
     };
     var doc = this;
-    return loadOptionalLibrary("canvg")
+    return loadCanvg()
       .then(
         function(canvg) {
           return canvg.Canvg.fromString(ctx, svg, options);