Convert minified js code to readable source code.
灵感来自于 https://github.com/pionxzh/wakaru/tree/main/packages/unminify, 正好最近也在学习 ast 逆向，所以打算自己实现这些 transformation。
- !0
+ true
- !1
+ false- void 0
+ undefined- 1 / 0
+ Infinity
- -1 / 0
+ -Infinity- 1e3
+ 1000 /* 1e3 */
- 0b101010
+ 42 /* 0b101010 */
- 0x123
+ 291 /* 0x123 */- if (x) foo()
+ if (x) {
+ foo()
+ }
- if (x)
- foo()
- else
- bar()
+ if (x) {
+ foo()
+ } else {
+ bar()
+ }
- for (;;) foo()
+ for (;;) {
+ foo()
+ }Separate variable declarators into multiple statements.
- var a = 1, b = true, c = func(d);
+ var a = 1;
+ var b = true;
+ var c = func(d);Separate variable declarators that are not used in for statements.
- for (var i = 0, j = 0, k = 0; j < 10; k++) {}
+ var i = 0;
+ for (var j = 0, k = 0; j < 10; k++) {}Separate sequence expression into multiple statements.
- a(), b(), c()
+ a()
+ b()
+ c()
- while (a(), b(), c++ > 0) {}
+ a()
+ b()
+ while (c++ > 0) {}
- return a(), b(), c()
+ a()
+ b()
+ return c()Separate chained assignment into multiple statements.
- a = b = c = 1
+ a = 1
+ b = 1
+ c = 1Simplify bracket notation.
- obj['prop']
+ obj.prop
- obj['var']
+ obj['var']Converts for loop without init and update to while loop.
- for (;;) {}
+ while (true) {}
- for (; i < 10;) {
- console.log(i);
- }
+ while (i < 10) {
+ console.log(i);
+ }Flips comparisons that are in the form of "literal comes first" to "literal comes second".
- if ("dark" === theme) {}
+ if (theme === "dark") {}
- while (10 < count) {}
+ while (count > 10) {}Unwraps nested ternary expressions and binary expression into if-else statements or switch statements.
- a ? b() : c ? d() : e()
+ if (a) {
+ b();
+ } else if (c) {
+ d();
+ } else {
+ e();
+ }Simplify the last return statements.
function foo() {
const a = 1;
if (a) {
return a;
}
- return void 0;
}
const bar = () => {
- return void foo();
+ foo();
}- Object.create;
- new WeakMap;
- Object.prototype.hasOwnProperty;- const {
- gql: t,
- dispatchers: o,
- listener: i
- } = n;
- o.delete(t, i);
+ const {
+ gql,
+ dispatchers,
+ listener
+ } = n;
+ dispatchers.delete(gql, listener);Improve the readability of code inside IIFE. Useful for short code snippets / userscripts.
Rename the parameters and move the passed-in arguments to the top.
- (function(i, s, o, g, r, a, m) {
- i['GoogleAnalyticsObject'] = r;
- i[r].l = 1 * new Date();
- a = s.createElement(o);
- m = s.getElementsByTagName(o)[0];
- a.async = 1;
- a.src = g;
- m.parentNode.insertBefore(a, m);
- })(window, document, 'script', 'https://www.google-analytics.com/analytics.js', 'ga');
+ (function(window, document, a, m) {
+ const o = 'script';
+ const g = 'https://www.google-analytics.com/analytics.js';
+ const r = 'ga';
+ window['GoogleAnalyticsObject'] = r;
+ window[r].l = 1 * new Date();
+ a = document.createElement(o);
+ m = document.getElementsByTagName(o)[0];
+ a.async = 1;
+ a.src = g;
+ m.parentNode.insertBefore(a, m);
+ })(window, document);Restore template literal syntax from string concatenation.
- "the ".concat(first, " take the ").concat(second, " and ").concat(third);
+ `the ${first} take the ${second} and ${third}`Restore parameters. Support normal parameters and default parameters.
- function foo() {
- var a = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : "foo";
- var b = arguments.length > 1 ? arguments[1] : undefined;
- if (c === void 0) c = "bar";
- }
+ function foo(a = "foo", b, c = "bar") {}Restore Class definition from the constructor and the prototype.
Currently, this transformation only supports output from TypeScript.
Supported features:
- constructor
- instance properties
- instance methods
- static methods
- static properties
- getters and setters
- async method (share the same limitations from
un-async-await)
Unsupported features:
- inheritance
- decorators
- private flag
- var Foo = (function() {
- function t(name) {
- this.name = name;
- this.age = 18;
- }
- t.prototype.hi = function logger() {
- console.log("Hello", this.name);
- };
- t.staticMethod = function staticMethod() {
- console.log("static");
- };
- t.instance = new t("foo");
- return t;
- })();
+ class Foo {
+ constructor(name) {
+ this.name = name;
+ this.age = 18;
+ }
+ hi() {
+ console.log("Hello", this.name);
+ }
+ static staticMethod() {
+ console.log("static");
+ }
+ static instance = new Foo("foo");
+ }Restore async/await from helper __awaiter and __generator.
Currently, this transformation only supports output from TypeScript.
And it does not handled control flow properly, as it needs graph analysis.
Please aware there are tons of edge cases that are not covered by this rule.
-function func() {
- return __awaiter(this, void 0, void 0, function () {
- var result, json;
- return __generator(this, function (_a) {
- switch (_a.label) {
- case 0:
- console.log('Before sleep');
- return [4 /*yield*/, sleep(1000)];
- case 1:
- _a.sent();
- return [4 /*yield*/, fetch('')];
- case 2:
- result = _a.sent();
- return [4 /*yield*/, result.json()];
- case 3:
- json = _a.sent();
- return [2 /*return*/, json];
- }
- });
- });
-}
+async function func() {
+ var result, json;
+ console.log('Before sleep');
+ await sleep(1000);
+ result = await fetch('');
+ json = await result.json();
+ return json;
+}Remove the __esModule flag from the module.
- Object.defineProperty(exports, "__esModule", { value: true });Remove the "use strict" directive.
- "use strict";Lebab transpiles your ES5 code to ES6/ES7. It does exactly the opposite of what Babel does.
We integrated part of rules from lebab to unminify the code.
By utilizing lebab, we can save the repetitive work of writing the same transformations ourselves.