dead_code_1: { options = { dead_code: true }; input: { function f() { a(); b(); x = 10; return; if (x) { y(); } } } expect: { function f() { a(); b(); x = 10; return; } } } dead_code_2_should_warn: { options = { dead_code: true }; input: { function f() { g(); x = 10; throw "foo"; // completely discarding the `if` would introduce some // bugs. UglifyJS v1 doesn't deal with this issue; in v2 // we copy any declarations to the upper scope. if (x) { y(); var x; function g(){}; // but nested declarations should not be kept. (function(){ var q; function y(){}; })(); } } } expect: { function f() { g(); x = 10; throw "foo"; var x; function g(){}; } } } dead_code_constant_boolean_should_warn_more: { options = { dead_code : true, loops : true, booleans : true, conditionals : true, evaluate : true }; input: { while (!((foo && bar) || (x + "0"))) { console.log("unreachable"); var foo; function bar() {} } for (var x = 10, y; x && (y || x) && (!typeof x); ++x) { asdf(); foo(); var moo; } } expect: { var foo; function bar() {} // nothing for the while // as for the for, it should keep: var x = 10, y; var moo; } } dead_code_const_declaration: { options = { dead_code : true, loops : true, booleans : true, conditionals : true, evaluate : true }; input: { var unused; const CONST_FOO = false; if (CONST_FOO) { console.log("unreachable"); var moo; function bar() {} } } expect: { var unused; const CONST_FOO = !1; var moo; function bar() {} } } dead_code_const_annotation: { options = { dead_code : true, loops : true, booleans : true, conditionals : true, evaluate : true }; input: { var unused; /** @const */ var CONST_FOO_ANN = false; if (CONST_FOO_ANN) { console.log("unreachable"); var moo; function bar() {} } } expect: { var unused; var CONST_FOO_ANN = !1; var moo; function bar() {} } } dead_code_const_annotation_regex: { options = { dead_code : true, loops : true, booleans : true, conditionals : true, evaluate : true }; input: { var unused; // @constraint this shouldn't be a constant var CONST_FOO_ANN = false; if (CONST_FOO_ANN) { console.log("reachable"); } } expect: { var unused; var CONST_FOO_ANN = !1; CONST_FOO_ANN && console.log('reachable'); } } dead_code_const_annotation_complex_scope: { options = { dead_code : true, loops : true, booleans : true, conditionals : true, evaluate : true }; input: { var unused_var; /** @const */ var test = 'test'; // @const var CONST_FOO_ANN = false; var unused_var_2; if (CONST_FOO_ANN) { console.log("unreachable"); var moo; function bar() {} } if (test === 'test') { var beef = 'good'; /** @const */ var meat = 'beef'; var pork = 'bad'; if (meat === 'pork') { console.log('also unreachable'); } else if (pork === 'good') { console.log('reached, not const'); } } } expect: { var unused_var; var test = 'test'; var CONST_FOO_ANN = !1; var unused_var_2; var moo; function bar() {} var beef = 'good'; var meat = 'beef'; var pork = 'bad'; 'good' === pork && console.log('reached, not const'); } }