lib.terser.js
function is_true(node) {
              return node instanceof AST_True
                  || in_bool
                      && node instanceof AST_Constant
                      && node.getValue()
                  || (node instanceof AST_UnaryPrefix
                      && node.operator == "!"
                      && node.expression instanceof AST_Constant
                      && !node.expression.getValue());
          }
function is_true(node) {
              return node instanceof AST_True
                  || in_bool
                      && node instanceof AST_Constant
                      && node.getValue()
                  || (node instanceof AST_UnaryPrefix
                      && node.operator == "!"
                      && node.expression instanceof AST_Constant
                      && !node.expression.getValue());
          }
function is_true ( node ) { return node instanceof AST_True || in_bool && node instanceof AST_Constant && node . getValue ( ) || ( node instanceof AST_UnaryPrefix && node . operator == "!" && node . expression instanceof AST_Constant && ! node . expression . getValue ( ) ) ; }
AST_True or !0
AST_True or !0