terser - npm Package Compare versions

Comparing version 5.16.9 to 5.17.0

CHANGELOG.md

 # Changelog
 
+## v5.17.0
+ - Drop vestigial `= undefined` default argument in IIFE calls (#1366)
+ - Evaluate known arrays' `.length` property when statically determinable
+ - Add `@__KEY__` annotation to mangle string literals (#1365)
+
 ## v5.16.9
@@ -4,0 +9,0 @@ - Fix parentheses in output of optional chains (`a?.b`) (#1374)

lib/compress/evaluate.js

@@ -355,2 +355,29 @@ /***********************************************************************
     if (obj === nullish || (this.optional && obj == null)) return nullish;
+
+    // `.length` of strings and arrays is always safe
+    if (this.property === "length") {
+        if (typeof obj === "string") {
+            return obj.length;
+        }
+
+        const is_spreadless_array = obj =>
+            obj instanceof AST_Array
+            && obj.elements.every(el => !(el instanceof AST_Expansion));
+
+        if (
+            is_spreadless_array(obj)
+            && obj.elements.every(el => !el.has_side_effects(compressor))
+        ) {
+            return obj.elements.length;
+        }
+
+        let fixed;
+        if (
+            obj instanceof AST_SymbolRef
+            && is_spreadless_array((fixed = obj.definition().fixed_value()))
+        ) {
+            return fixed.elements.length;
+        }
+    }
+
     if (compressor.option("unsafe")) {
@@ -363,5 +390,5 @@ var key = this.property;
         }
+
         var exp = this.expression;
         if (is_undeclared_ref(exp)) {
-
             var aa;
@@ -368,0 +395,0 @@ var first_arg = exp.name === "hasOwnProperty"

lib/propmangle.js

@@ -50,2 +50,4 @@ /***********************************************************************
     push_uniq,
+    has_annotation,
+    clear_annotation,
 } from "./utils/index.js";
@@ -71,2 +73,3 @@ import { base54 } from "./scope.js";
     TreeWalker,
+    _KEY,
 } from "./ast.js";
@@ -268,2 +271,4 @@ import { domprops } from "../tools/domprops.js";
             addStrings(node.left, add);
+        } else if (node instanceof AST_String && has_annotation(node, _KEY)) {
+            add(node.value);
         }
@@ -302,2 +307,6 @@ }));
             node.left = mangleStrings(node.left);
+        } else if (node instanceof AST_String && has_annotation(node, _KEY)) {
+            // Clear _KEY annotation to prevent double mangling
+            clear_annotation(node, _KEY);
+            node.value = mangle(node.value);
         }
@@ -368,2 +377,4 @@ }));
             } else if (node instanceof AST_String) {
+                // Clear _KEY annotation to prevent double mangling
+                clear_annotation(node, _KEY);
                 node.value = mangle(node.value);
@@ -370,0 +381,0 @@ } else if (node instanceof AST_Conditional) {

lib/utils/index.js

@@ -265,2 +265,6 @@ /***********************************************************************
 
+function clear_annotation(node, annotation) {
+    node._annotations &= ~annotation;
+}
+
 export {
@@ -290,3 +294,4 @@ characters,
     has_annotation,
-    set_annotation
+    set_annotation,
+    clear_annotation,
 };

package.json

@@ -7,3 +7,3 @@ {
   "license": "BSD-2-Clause",
-  "version": "5.16.9",
+  "version": "5.17.0",
   "engines": {
@@ -10,0 +10,0 @@ "node": ">=10"

README.md

@@ -1191,2 +1191,3 @@ <h1><img src="https://terser.org/img/terser-banner-logo.png" alt="Terser" width="400"></h1>
  * `/*@__PURE__*/` - Marks a function call as pure. That means, it can safely be dropped.
+ * `/*@__KEY__*/` - Marks a string literal as a property to also mangle it when mangling properties.
 
@@ -1205,2 +1206,5 @@ You can use either a `@` sign at the start, or a `#`.
 const x = /*#__PURE__*/i_am_dropped_if_x_is_not_used()
+
+function lookup(object, key) { return object[key]; }
+lookup({ i_will_be_mangled_too: "bar" }, /*@__KEY__*/ "i_will_be_mangled_too");
 ```
@@ -1207,0 +1211,0 @@

No alert changes

Improved metrics

Total package byte prevSize

2080707

0.2%

Lines of code

59189

0.17%

Number of lines in readme file

1389

0.29%

No dependency changes