babel-plugin-minify-dead-code-elimination - npm Package Compare versions

Comparing version 0.0.4 to 0.1.0

lib/index.js

 "use strict";
 
-var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol ? "symbol" : typeof obj; };
+var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };
 
@@ -10,4 +10,4 @@ function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }
 module.exports = function (_ref) {
-  var t = _ref.types;
-  var traverse = _ref.traverse;
+  var t = _ref.types,
+      traverse = _ref.traverse;
 
@@ -17,2 +17,7 @@ var removeOrVoid = require("babel-helper-remove-or-void")(t);
 
+  // this is used for tracking fn params that can be removed
+  // as traversal takes place from left and
+  // unused params can be removed only on the right
+  var markForRemoval = Symbol("markForRemoval");
+
   var main = {
@@ -40,4 +45,4 @@ // remove side effectless statement
 
-        var node = path.node;
-        var scope = path.scope;
+        var node = path.node,
+            scope = path.scope;
 
@@ -182,9 +187,54 @@ var seen = new Set();
 
+        // if the scope is created by a function, we obtain its
+        // parameter list
+
+        var paramsList = path.isFunction() ? path.get("params") : [];
+
+        for (var i = paramsList.length - 1; i >= 0; i--) {
+          var param = paramsList[i];
+
+          if (param.isIdentifier()) {
+            var binding = scope.bindings[param.node.name];
+            if (binding.referenced) {
+              // when the first binding is referenced (right to left)
+              // exit without marking anything after this
+              break;
+            }
+
+            binding[markForRemoval] = true;
+            continue;
+          } else if (param.isAssignmentPattern()) {
+            var left = param.get("left");
+            var right = param.get("right");
+
+            if (left.isIdentifier() && right.isPure()) {
+              var _binding = scope.bindings[left.node.name];
+              if (_binding.referenced) {
+                // when the first binding is referenced (right to left)
+                // exit without marking anything after this
+                break;
+              }
+
+              _binding[markForRemoval] = true;
+              continue;
+            }
+          }
+
+          // other patterns - assignment, object have side-effects
+          // and cannot be safely removed
+          break;
+        }
+
         var _loop3 = function _loop3(name) {
           var binding = scope.bindings[name];
-          if (!binding.referenced && binding.kind !== "param" && binding.kind !== "module") {
+
+          if (!binding.referenced && binding.kind !== "module") {
             var _ret4 = function () {
-              if (binding.path.isVariableDeclarator()) {
-                if (binding.path.parentPath.parentPath && binding.path.parentPath.parentPath.isForInStatement()) {
-                  // Can't remove if in a for in statement `for (var x in wat)`.
+              if (binding.kind === "param" && (_this.keepFnArgs || !binding[markForRemoval])) {
+                return {
+                  v: "continue"
+                };
+              } else if (binding.path.isVariableDeclarator()) {
+                if (binding.path.parentPath.parentPath && binding.path.parentPath.parentPath.isForXStatement()) {
+                  // Can't remove if in a for-in/for-of/for-await statement `for (var x in wat)`.
                   return {
@@ -195,2 +245,3 @@ v: "continue"
               } else if (!scope.isPure(binding.path.node)) {
+                // TODO: AssignmentPattern are marked as impure and unused ids aren't removed yet
                 return {
@@ -241,2 +292,8 @@ v: "continue"
                 }
+                // Bail out for ArrayPattern and ObjectPattern
+                if (!binding.path.get("id").isIdentifier()) {
+                  return {
+                    v: "continue"
+                  };
+                }
 
@@ -719,3 +776,3 @@ binding.path.parentPath.replaceWith(binding.path.node.init);
     "FunctionExpression|ClassExpression": function FunctionExpressionClassExpression(path) {
-      if (!this.keepFnames) {
+      if (!this.keepFnName) {
         removeUnreferencedId(path);
@@ -770,10 +827,12 @@ }
       Program: function Program(path) {
-        var _ref4 = arguments.length <= 1 || arguments[1] === undefined ? {} : arguments[1];
+        var _ref4 = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {},
+            _ref4$opts = _ref4.opts;
 
-        var _ref4$opts = _ref4.opts;
         _ref4$opts = _ref4$opts === undefined ? {} : _ref4$opts;
-        var _ref4$opts$optimizeRa = _ref4$opts.optimizeRawSize;
-        var optimizeRawSize = _ref4$opts$optimizeRa === undefined ? false : _ref4$opts$optimizeRa;
-        var _ref4$opts$keepFnames = _ref4$opts.keepFnames;
-        var keepFnames = _ref4$opts$keepFnames === undefined ? false : _ref4$opts$keepFnames;
+        var _ref4$opts$optimizeRa = _ref4$opts.optimizeRawSize,
+            optimizeRawSize = _ref4$opts$optimizeRa === undefined ? false : _ref4$opts$optimizeRa,
+            _ref4$opts$keepFnName = _ref4$opts.keepFnName,
+            keepFnName = _ref4$opts$keepFnName === undefined ? false : _ref4$opts$keepFnName,
+            _ref4$opts$keepFnArgs = _ref4$opts.keepFnArgs,
+            keepFnArgs = _ref4$opts$keepFnArgs === undefined ? false : _ref4$opts$keepFnArgs;
 
@@ -784,3 +843,4 @@ // We need to run this plugin in isolation.
           optimizeRawSize: optimizeRawSize,
-          keepFnames: keepFnames
+          keepFnName: keepFnName,
+          keepFnArgs: keepFnArgs
         });
@@ -885,5 +945,5 @@ }
   function replace(path, options) {
-    var replacement = options.replacement;
-    var scope = options.scope;
-    var binding = options.binding;
+    var replacement = options.replacement,
+        scope = options.scope,
+        binding = options.binding;
 
@@ -958,4 +1018,4 @@ // Same name, different binding.
       ReferencedIdentifier: function ReferencedIdentifier(path) {
-        var node = path.node;
-        var scope = path.scope;
+        var node = path.node,
+            scope = path.scope;
 
@@ -991,4 +1051,4 @@ var binding = scope.getBinding(node.name);
 
-    var node = path.node;
-    var scope = path.scope;
+    var node = path.node,
+        scope = path.scope;
 
@@ -1059,3 +1119,9 @@ var binding = scope.getBinding(id.name);
         // if they are within the case, we keep them
-        var _isAncestor = isAncestor(path.scope.getBinding(label.node.name).path, path);
+        var labelPath = void 0;
+        if (path.scope.getLabel) {
+          labelPath = getLabel(label.node.name, path);
+        } else {
+          labelPath = path.scope.getBinding(label.node.name).path;
+        }
+        var _isAncestor = isAncestor(labelPath, path);
 
@@ -1121,2 +1187,14 @@ return {
   }
+
+  function getLabel(name, _path) {
+    var label = void 0,
+        path = _path;
+    do {
+      label = path.scope.getLabel(name);
+      if (label) {
+        return label;
+      }
+    } while (path = path.parentPath);
+    return null;
+  }
 };

package.json

 {
   "name": "babel-plugin-minify-dead-code-elimination",
-  "version": "0.0.4",
+  "version": "0.1.0",
   "description": "",
@@ -5,0 +5,0 @@ "homepage": "https://github.com/babel/babili#readme",

README.md

@@ -70,2 +70,3 @@ # babel-plugin-minify-dead-code-elimination
 
-+ `keepFnames` - prevent plugin from removing function names. Useful for code depending on `fn.name`
++ `keepFnName` - prevent plugin from removing function name. Useful for code depending on `fn.name`
++ `keepFnArgs` - prevent plugin from removing function args. Useful for code depending on `fn.length`

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Found 1 instance in 1 package

Fixed alerts

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Improved metrics

Total package byte prevSize

39336

increased by7.56%

Lines of code

999

increased by7.19%

Number of lines in readme file

72

increased by1.41%

No dependency changes