visitor/calculate-binary: check if left and right are both constants …

…before replacing

Signed-off-by: echo094 <[email protected]>

src/visitor/calculate-binary.js

@@ -1,7 +1,18 @@
 const generator = require('@babel/generator').default
+const t = require('@babel/types')
 
+/**
+ * Calculate BinaryExpression if left and right are both literals.
+ * Otherwise, the expression can't be simplified.
+ *
+ * For example, `typeof window` can be calculated but it's not constant.
+ */
 module.exports = {
   BinaryExpression(path) {
+    const { left, right } = path.node
+    if (!t.isLiteral(left) || !t.isLiteral(right)) {
+      return
+    }
     const code = generator(path.node).code
     try {
       const ret = eval(code)