flow like the river

VISUALIZACION/node_modules/htmlnano/lib/modules/minifyJs.js

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+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = minifyJs;
+
+var _terser = require('terser');
+
+var _terser2 = _interopRequireDefault(_terser);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/** Minify JS with Terser */
+function minifyJs(tree, options, terserOptions) {
+
+    tree.match({ tag: 'script' }, function (node) {
+        var nodeAttrs = node.attrs || {};
+        var mimeType = nodeAttrs.type || 'text/javascript';
+        if (mimeType === 'text/javascript' || mimeType === 'application/javascript') {
+            return processScriptNode(node, terserOptions);
+        }
+
+        return node;
+    });
+
+    tree.match({ attrs: true }, function (node) {
+        return processNodeWithOnAttrs(node, terserOptions);
+    });
+
+    return tree;
+}
+
+function processScriptNode(scriptNode, terserOptions) {
+    var js = (scriptNode.content || []).join(' ').trim();
+    if (!js) {
+        return scriptNode;
+    }
+
+    var result = _terser2.default.minify(js, terserOptions);
+    if (result.error) {
+        throw new Error(result.error);
+    }
+    if (result.code === undefined) {
+        return scriptNode;
+    }
+
+    scriptNode.content = [result.code];
+
+    return scriptNode;
+}
+
+function processNodeWithOnAttrs(node, terserOptions) {
+    var jsWrapperStart = 'function _(){';
+    var jsWrapperEnd = '}';
+
+    var _iteratorNormalCompletion = true;
+    var _didIteratorError = false;
+    var _iteratorError = undefined;
+
+    try {
+        for (var _iterator = Object.keys(node.attrs || {})[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
+            var attrName = _step.value;
+
+            if (attrName.search('on') !== 0) {
+                continue;
+            }
+
+            // For example onclick="return false" is valid,
+            // but "return false;" is invalid (error: 'return' outside of function)
+            // Therefore the attribute's code should be wrapped inside function:
+            // "function _(){return false;}"
+            var wrappedJs = jsWrapperStart + node.attrs[attrName] + jsWrapperEnd;
+            var wrappedMinifiedJs = _terser2.default.minify(wrappedJs, terserOptions).code;
+            var minifiedJs = wrappedMinifiedJs.substring(jsWrapperStart.length, wrappedMinifiedJs.length - jsWrapperEnd.length);
+            node.attrs[attrName] = minifiedJs;
+        }
+    } catch (err) {
+        _didIteratorError = true;
+        _iteratorError = err;
+    } finally {
+        try {
+            if (!_iteratorNormalCompletion && _iterator.return) {
+                _iterator.return();
+            }
+        } finally {
+            if (_didIteratorError) {
+                throw _iteratorError;
+            }
+        }
+    }
+
+    return node;
+}