CODEWITHSUNDEEP
javascriptrenameabstract-syntax-tree
Att Righ
Att Righ

Reputation: 1799

Javascript: safe replace function or variable name?

I'm working with some deminified javascript that I want to reverse engineer. It would be helpful if I could start giving things variable names. Unfortunately the code has a habit of reusing function and variable names globally and in function scopes, how can I safely replace variable names in these cases in an ast-aware way?

Upvotes: 0

Views: 593

Answers (1)

coderaiser
coderaiser

Reputation: 827

The simplest way would be to use 🐊Putout code transformer, I'm working on. Here is the code:

export const fix = ({path, names}) => {
    const {name} = path.node;
    const to = names[name];
    
    path.scope.rename(name, to);
}

export const traverse = ({push}) =>  {
    const names = {
        a: 'username',
        b: 'password',
    };
    
    const namesKeys = Object.keys(names);
    
    return {
        Identifier(path) {
            const {name} = path.node;
            const bindings = path.scope.getAllBindings();
            
            if (namesKeys.includes(name) && bindings[name])
                push({
                    path,
                    names,
                });
        }
    };
};

From:

const a = 'John';
const b = 'Wick';

login();

function login() {
    if (a)
        log(a);

    if (b)
        log(b);
}

To:

const username = 'John';
const password = 'Wick';

login();

function login() {
    if (username)
        log(username);

    if (password)
        log(password);
}

You can get realtime results in 🐊Putout Editor, just modify names map with a values you need.

Upvotes: 2

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