From fad6766a905350574b698af707958294e22184f3 Mon Sep 17 00:00:00 2001 From: "Alex Lam S.L" Date: Thu, 1 Feb 2018 16:50:54 +0800 Subject: [PATCH] simplify comparisons with `undefined` & `null` (#2862) fixes #2857 --- lib/compress.js | 28 ++++++++ test/compress/comparing.js | 130 +++++++++++++++++++++++++++++++++++++ 2 files changed, 158 insertions(+) diff --git a/lib/compress.js b/lib/compress.js index b4d13ec7..a88ea2c4 100644 --- a/lib/compress.js +++ b/lib/compress.js @@ -4788,6 +4788,34 @@ merge(Compressor.prototype, { return make_node(self.operator[0] == "=" ? AST_True : AST_False, self); } break; + case "&&": + case "||": + var lhs = self.left; + if (lhs.operator == self.operator) { + lhs = lhs.right; + } + if (lhs instanceof AST_Binary + && lhs.operator == (self.operator == "&&" ? "!==" : "===") + && self.right instanceof AST_Binary + && lhs.operator == self.right.operator + && (is_undefined(lhs.left, compressor) && self.right.left instanceof AST_Null + || lhs.left instanceof AST_Null && is_undefined(self.right.left, compressor)) + && lhs.right.equivalent_to(self.right.right)) { + var combined = make_node(AST_Binary, self, { + operator: lhs.operator.slice(0, -1), + left: make_node(AST_Null, self), + right: lhs.right + }); + if (lhs !== self.left) { + combined = make_node(AST_Binary, self, { + operator: self.operator, + left: self.left.left, + right: combined + }); + } + return combined; + } + break; } if (self.operator == "+" && compressor.in_boolean_context()) { var ll = self.left.evaluate(compressor); diff --git a/test/compress/comparing.js b/test/compress/comparing.js index e374b585..d581d086 100644 --- a/test/compress/comparing.js +++ b/test/compress/comparing.js @@ -112,3 +112,133 @@ self_comparison_2: { } expect_stdout: "false true" } + +issue_2857_1: { + options = { + comparisons: true, + } + input: { + a === undefined || a === null; + a === undefined || a !== null; + a !== undefined || a === null; + a !== undefined || a !== null; + a === undefined && a === null; + a === undefined && a !== null; + a !== undefined && a === null; + a !== undefined && a !== null; + } + expect: { + null == a; + void 0 === a || null !== a; + void 0 !== a || null === a; + void 0 !== a || null !== a; + void 0 === a && null === a; + void 0 === a && null !== a; + void 0 !== a && null === a; + null != a; + } +} + +issue_2857_2: { + options = { + comparisons: true, + } + input: { + a === undefined || a === null || p; + a === undefined || a !== null || p; + a !== undefined || a === null || p; + a !== undefined || a !== null || p; + a === undefined && a === null || p; + a === undefined && a !== null || p; + a !== undefined && a === null || p; + a !== undefined && a !== null || p; + } + expect: { + null == a || p; + void 0 === a || null !== a || p; + void 0 !== a || null === a || p; + void 0 !== a || null !== a || p; + void 0 === a && null === a || p; + void 0 === a && null !== a || p; + void 0 !== a && null === a || p; + null != a || p; + } +} + +issue_2857_3: { + options = { + comparisons: true, + } + input: { + a === undefined || a === null && p; + a === undefined || a !== null && p; + a !== undefined || a === null && p; + a !== undefined || a !== null && p; + a === undefined && a === null && p; + a === undefined && a !== null && p; + a !== undefined && a === null && p; + a !== undefined && a !== null && p; + } + expect: { + void 0 === a || null === a && p; + void 0 === a || null !== a && p; + void 0 !== a || null === a && p; + void 0 !== a || null !== a && p; + void 0 === a && null === a && p; + void 0 === a && null !== a && p; + void 0 !== a && null === a && p; + null != a && p; + } +} + +issue_2857_4: { + options = { + comparisons: true, + } + input: { + p || a === undefined || a === null; + p || a === undefined || a !== null; + p || a !== undefined || a === null; + p || a !== undefined || a !== null; + p || a === undefined && a === null; + p || a === undefined && a !== null; + p || a !== undefined && a === null; + p || a !== undefined && a !== null; + } + expect: { + p || null == a; + p || void 0 === a || null !== a; + p || void 0 !== a || null === a; + p || void 0 !== a || null !== a; + p || void 0 === a && null === a; + p || void 0 === a && null !== a; + p || void 0 !== a && null === a; + p || null != a; + } +} + +issue_2857_5: { + options = { + comparisons: true, + } + input: { + p && a === undefined || a === null; + p && a === undefined || a !== null; + p && a !== undefined || a === null; + p && a !== undefined || a !== null; + p && a === undefined && a === null; + p && a === undefined && a !== null; + p && a !== undefined && a === null; + p && a !== undefined && a !== null; + } + expect: { + p && void 0 === a || null === a; + p && void 0 === a || null !== a; + p && void 0 !== a || null === a; + p && void 0 !== a || null !== a; + p && void 0 === a && null === a; + p && void 0 === a && null !== a; + p && void 0 !== a && null === a; + p && null != a; + } +} -- 2.34.1