diff --git a/javascript/extractor/src/com/semmle/jcorn/Parser.java b/javascript/extractor/src/com/semmle/jcorn/Parser.java
index 63f49e148911..b0bc89645597 100644
--- a/javascript/extractor/src/com/semmle/jcorn/Parser.java
+++ b/javascript/extractor/src/com/semmle/jcorn/Parser.java
@@ -286,6 +286,7 @@ protected void raise(int pos, String msg) {
     raise(pos, msg, false);
   }
 
+  @SuppressWarnings("ReturnValueIgnored")
   protected void raise(Position loc, String msg, boolean recoverable) {
     msg += " (" + loc.getLine() + ":" + loc.getColumn() + ")";
     SyntaxError err = new SyntaxError(msg, loc, this.pos);
@@ -3114,7 +3115,7 @@ protected BlockStatement parseBlock(boolean allowStrict) {
       }
       first = false;
     }
-    if (oldStrict == Boolean.FALSE) this.setStrict(false);
+    if (Boolean.FALSE.equals(oldStrict)) this.setStrict(false);
     return this.finishNode(new BlockStatement(new SourceLocation(startLoc), body));
   }
 
diff --git a/javascript/extractor/src/com/semmle/jcorn/flow/FlowParser.java b/javascript/extractor/src/com/semmle/jcorn/flow/FlowParser.java
index cb2dad0f978a..7475994c27ed 100644
--- a/javascript/extractor/src/com/semmle/jcorn/flow/FlowParser.java
+++ b/javascript/extractor/src/com/semmle/jcorn/flow/FlowParser.java
@@ -141,6 +141,7 @@ private void reset() {
       options.onRecoverableError(this.onRecoverableError);
     }
 
+    @SuppressWarnings("ReturnValueIgnored")
     private void commit() {
       // commit buffered tokens
       options.onToken(this.onToken);
diff --git a/javascript/extractor/src/com/semmle/js/ast/AFunctionExpression.java b/javascript/extractor/src/com/semmle/js/ast/AFunctionExpression.java
index e097be125cf8..1546d6f3b1f7 100644
--- a/javascript/extractor/src/com/semmle/js/ast/AFunctionExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/AFunctionExpression.java
@@ -35,8 +35,8 @@ public AFunctionExpression(
             id,
             params,
             body,
-            generator == Boolean.TRUE,
-            async == Boolean.TRUE,
+            Boolean.TRUE.equals(generator),
+            Boolean.TRUE.equals(async),
             typeParameters,
             parameterTypes,
             parameterDecorators,
diff --git a/javascript/extractor/src/com/semmle/js/ast/ComprehensionBlock.java b/javascript/extractor/src/com/semmle/js/ast/ComprehensionBlock.java
index 4c767c5fbed0..4fcf9421a745 100644
--- a/javascript/extractor/src/com/semmle/js/ast/ComprehensionBlock.java
+++ b/javascript/extractor/src/com/semmle/js/ast/ComprehensionBlock.java
@@ -10,7 +10,7 @@ public ComprehensionBlock(SourceLocation loc, IPattern left, Expression right, B
     super("ComprehensionBlock", loc);
     this.left = left;
     this.right = right;
-    this.of = of != Boolean.FALSE;
+    this.of = !Boolean.FALSE.equals(of);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/ComprehensionExpression.java b/javascript/extractor/src/com/semmle/js/ast/ComprehensionExpression.java
index b95d9ead5ff2..3aa9feb1b312 100644
--- a/javascript/extractor/src/com/semmle/js/ast/ComprehensionExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/ComprehensionExpression.java
@@ -19,7 +19,7 @@ public ComprehensionExpression(
     this.body = body;
     this.blocks = blocks;
     this.filter = filter;
-    this.generator = generator == Boolean.TRUE;
+    this.generator = Boolean.TRUE.equals(generator);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/ForInStatement.java b/javascript/extractor/src/com/semmle/js/ast/ForInStatement.java
index 579a6198fe12..cffba4781a9b 100644
--- a/javascript/extractor/src/com/semmle/js/ast/ForInStatement.java
+++ b/javascript/extractor/src/com/semmle/js/ast/ForInStatement.java
@@ -16,7 +16,7 @@ public class ForInStatement extends EnhancedForStatement {
   public ForInStatement(
       SourceLocation loc, Node left, Expression right, Statement body, Boolean each) {
     super("ForInStatement", loc, left, right, body);
-    this.each = each == Boolean.TRUE;
+    this.each = Boolean.TRUE.equals(each);
   }
 
   public boolean isEach() {
diff --git a/javascript/extractor/src/com/semmle/js/ast/InvokeExpression.java b/javascript/extractor/src/com/semmle/js/ast/InvokeExpression.java
index 534f9ffb2121..5d59be92f1b5 100644
--- a/javascript/extractor/src/com/semmle/js/ast/InvokeExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/InvokeExpression.java
@@ -27,8 +27,8 @@ public InvokeExpression(
     this.callee = callee;
     this.typeArguments = typeArguments;
     this.arguments = arguments;
-    this.optional = optional == Boolean.TRUE;
-    this.onOptionalChain = onOptionalChain == Boolean.TRUE;
+    this.optional = Boolean.TRUE.equals(optional);
+    this.onOptionalChain = Boolean.TRUE.equals(onOptionalChain);
   }
 
   /** The callee expression of this invocation. */
diff --git a/javascript/extractor/src/com/semmle/js/ast/Literal.java b/javascript/extractor/src/com/semmle/js/ast/Literal.java
index 3c53798b8512..f513adc14b56 100644
--- a/javascript/extractor/src/com/semmle/js/ast/Literal.java
+++ b/javascript/extractor/src/com/semmle/js/ast/Literal.java
@@ -76,7 +76,7 @@ public boolean isFalsy() {
     if (isRegExp()) return false;
     return value == null
         || value instanceof Number && ((Number) value).intValue() == 0
-        || value == Boolean.FALSE
+        || Boolean.FALSE.equals(value)
         || value instanceof String && ((String) value).isEmpty();
   }
 
diff --git a/javascript/extractor/src/com/semmle/js/ast/MemberExpression.java b/javascript/extractor/src/com/semmle/js/ast/MemberExpression.java
index b540decd48e7..342fe4c1fd2a 100644
--- a/javascript/extractor/src/com/semmle/js/ast/MemberExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/MemberExpression.java
@@ -22,9 +22,9 @@ public MemberExpression(
     super("MemberExpression", loc);
     this.object = object;
     this.property = property;
-    this.computed = computed == Boolean.TRUE;
-    this.optional = optional == Boolean.TRUE;
-    this.onOptionalChain = onOptionalChain == Boolean.TRUE;
+    this.computed = Boolean.TRUE.equals(computed);
+    this.optional = Boolean.TRUE.equals(optional);
+    this.onOptionalChain = Boolean.TRUE.equals(onOptionalChain);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/Property.java b/javascript/extractor/src/com/semmle/js/ast/Property.java
index b4da797e76d2..7f986161fde3 100644
--- a/javascript/extractor/src/com/semmle/js/ast/Property.java
+++ b/javascript/extractor/src/com/semmle/js/ast/Property.java
@@ -59,8 +59,8 @@ public Property(
     }
     this.rawValue = rawValue;
     this.kind = Kind.valueOf(StringUtil.uc(kind));
-    this.computed = computed == Boolean.TRUE;
-    this.method = method == Boolean.TRUE;
+    this.computed = Boolean.TRUE.equals(computed);
+    this.method = Boolean.TRUE.equals(method);
     this.decorators = new ArrayList<Decorator>();
   }
 
diff --git a/javascript/extractor/src/com/semmle/js/ast/TemplateElement.java b/javascript/extractor/src/com/semmle/js/ast/TemplateElement.java
index afebf51e7ee5..3fb8556e2735 100644
--- a/javascript/extractor/src/com/semmle/js/ast/TemplateElement.java
+++ b/javascript/extractor/src/com/semmle/js/ast/TemplateElement.java
@@ -10,7 +10,7 @@ public TemplateElement(SourceLocation loc, Object cooked, String raw, Boolean ta
     super("TemplateElement", loc);
     this.cooked = cooked;
     this.raw = raw;
-    this.tail = tail == Boolean.TRUE;
+    this.tail = Boolean.TRUE.equals(tail);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/UnaryExpression.java b/javascript/extractor/src/com/semmle/js/ast/UnaryExpression.java
index c0a77e3bc774..32f43bad1237 100644
--- a/javascript/extractor/src/com/semmle/js/ast/UnaryExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/UnaryExpression.java
@@ -14,7 +14,7 @@ public UnaryExpression(SourceLocation loc, String operator, Expression argument,
     super("UnaryExpression", loc);
     this.operator = operator;
     this.argument = argument;
-    this.prefix = prefix == Boolean.TRUE;
+    this.prefix = Boolean.TRUE.equals(prefix);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/UpdateExpression.java b/javascript/extractor/src/com/semmle/js/ast/UpdateExpression.java
index 59a3880a3ee5..1c69a1dd1501 100644
--- a/javascript/extractor/src/com/semmle/js/ast/UpdateExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/UpdateExpression.java
@@ -11,7 +11,7 @@ public UpdateExpression(
     super("UpdateExpression", loc);
     this.operator = operator;
     this.argument = argument;
-    this.prefix = prefix == Boolean.TRUE;
+    this.prefix = Boolean.TRUE.equals(prefix);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/YieldExpression.java b/javascript/extractor/src/com/semmle/js/ast/YieldExpression.java
index c8c681d24932..abd5fd13d110 100644
--- a/javascript/extractor/src/com/semmle/js/ast/YieldExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/YieldExpression.java
@@ -8,7 +8,7 @@ public class YieldExpression extends Expression {
   public YieldExpression(SourceLocation loc, Expression argument, Boolean delegating) {
     super("YieldExpression", loc);
     this.argument = argument;
-    this.delegating = delegating == Boolean.TRUE;
+    this.delegating = Boolean.TRUE.equals(delegating);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/jsdoc/FunctionType.java b/javascript/extractor/src/com/semmle/js/ast/jsdoc/FunctionType.java
index d9298243be0f..c344f9437208 100644
--- a/javascript/extractor/src/com/semmle/js/ast/jsdoc/FunctionType.java
+++ b/javascript/extractor/src/com/semmle/js/ast/jsdoc/FunctionType.java
@@ -18,7 +18,7 @@ public FunctionType(
       JSDocTypeExpression result) {
     super(loc, "FunctionType");
     this._this = _this;
-    this._new = _new == Boolean.TRUE;
+    this._new = Boolean.TRUE.equals(_new);
     this.params = params;
     this.result = result;
   }
diff --git a/javascript/extractor/src/com/semmle/js/ast/jsdoc/UnaryTypeConstructor.java b/javascript/extractor/src/com/semmle/js/ast/jsdoc/UnaryTypeConstructor.java
index dcded09e66d2..1489f9242517 100644
--- a/javascript/extractor/src/com/semmle/js/ast/jsdoc/UnaryTypeConstructor.java
+++ b/javascript/extractor/src/com/semmle/js/ast/jsdoc/UnaryTypeConstructor.java
@@ -19,7 +19,7 @@ public UnaryTypeConstructor(
       String operator) {
     super(loc, type);
     this.expression = expression;
-    this.prefix = prefix == Boolean.TRUE;
+    this.prefix = Boolean.TRUE.equals(prefix);
     this.operator = operator;
   }
 
diff --git a/javascript/extractor/src/com/semmle/js/ast/regexp/CharacterClass.java b/javascript/extractor/src/com/semmle/js/ast/regexp/CharacterClass.java
index 6a46830d851b..a0d5812efe66 100644
--- a/javascript/extractor/src/com/semmle/js/ast/regexp/CharacterClass.java
+++ b/javascript/extractor/src/com/semmle/js/ast/regexp/CharacterClass.java
@@ -11,7 +11,7 @@ public class CharacterClass extends RegExpTerm {
   public CharacterClass(SourceLocation loc, List<RegExpTerm> elements, Boolean inverted) {
     super(loc, "CharacterClass");
     this.elements = elements;
-    this.inverted = inverted == Boolean.TRUE;
+    this.inverted = Boolean.TRUE.equals(inverted);
   }
 
   @Override
diff --git a/javascript/extractor/src/com/semmle/js/ast/regexp/Quantifier.java b/javascript/extractor/src/com/semmle/js/ast/regexp/Quantifier.java
index 54fd40168d26..18058c73fb15 100644
--- a/javascript/extractor/src/com/semmle/js/ast/regexp/Quantifier.java
+++ b/javascript/extractor/src/com/semmle/js/ast/regexp/Quantifier.java
@@ -10,7 +10,7 @@ public abstract class Quantifier extends RegExpTerm {
   public Quantifier(SourceLocation loc, String type, RegExpTerm operand, Boolean greedy) {
     super(loc, type);
     this.operand = operand;
-    this.greedy = greedy == Boolean.TRUE;
+    this.greedy = Boolean.TRUE.equals(greedy);
   }
 
   /** The quantified term. */