normalize-function args from extracted code

extracted-code-example.js

let funcCode = '(n) => { "ArrowDown" === n.key && n.preventDefault() }';
let { needsNormalization, normalizedCode } = normalizeFunction(funcCode, 'e');
console.log(needsNormalization); 
console.log(normalizedCode); 

normalize-fn.js

const { parse, traverse, generate } = require("@babel/core");

function normalizeFunction(funcCode) {
    const parsed = parse(funcCode);
    let needsNormalization = false;
    let originalArgNames = {};

    traverse(parsed, {
        FunctionExpression(path) {
            const params = path.node.params;
            // If the function has parameters
            if (params.length > 0) {
                needsNormalization = true;
                originalArgNames.first = params[0].name;
                params[0].name = 'e';
                // If the function has a second parameter
                if (params[1]) {
                    originalArgNames.second = params[1].name;
                    params[1].name = 't';
                }
            }
        }
    });

    if (needsNormalization) {
        // replace all 'originalArgNames.first' variable references with 'e'
        // and 'originalArgNames.second' variable references with 't'
        traverse(parsed, {
            Identifier(path) {
                if (path.node.name === originalArgNames.first) {
                    path.node.name = 'e';
                } else if (path.node.name === originalArgNames.second) {
                    path.node.name = 't';
                }
            }
        });
    }

    return {
        needsNormalization,
        normalizedCode: needsNormalization ? generate(parsed).code : funcCode
    };
}

normalize-fn.min.js

const { parse, traverse, generate } = require("@babel/core");
const Terser = require("terser");

function normalizeFunction(funcCode) {
    const parsed = parse(funcCode);
    let needsNormalization = false;
    let originalArgNames = {};

    traverse(parsed, {
        FunctionExpression(path) {
            const params = path.node.params;
            // If the function has parameters
            if (params.length > 0) {
                needsNormalization = true;
                originalArgNames.first = params[0].name;
                params[0].name = 'e';
                // If function has a second parameter
                if (params[1]) {
                    originalArgNames.second = params[1].name;
                    params[1].name = 't';
                }
            }
        }
    });

    if (needsNormalization) {
        // replace all 'originalArgNames.first' variable references with 'e'
        // and 'originalArgNames.second' variable references with 't'
        traverse(parsed, {
            Identifier(path) {
                if (path.node.name === originalArgNames.first) {
                    path.node.name = 'e';
                } else if (path.node.name === originalArgNames.second) {
                    path.node.name = 't';
                }
            }
        });
    }
  
    const normalizedCode = needsNormalization ? generate(parsed).code : funcCode;
  
    // Minify with Terser
    const minifiedCode = Terser.minify(normalizedCode).code;
  
    return {
        needsNormalization,
        normalizedCode: minifiedCode
    };
}

shouldNormalize.js

function shouldNormalize(funcCode) {
    const funcRegex = /^\s*[(]\s*([^)\s]+)/;
    const match = funcCode.match(funcRegex);
    return match ? match[1] !== 'e' : false;
}

let funcCode = '(n) => { "ArrowDown" === n.key && n.preventDefault() }';
if (shouldNormalize(funcCode)) {
    let { needsNormalization, normalizedCode } = normalizeFunction(funcCode, 'e');
    console.log(needsNormalization);
    console.log(normalizedCode);
}

• e=>console.log(e) -> e=>console.log(e);
• (e, t)=>console.log(e) -> (e,t)=>console.log(e);
• (_, t)=>console.log(t) -> (e,t)=>console.log(t);
• ()=>console.log('hi') -> ()=>console.log("hi");
• evt=>console.log(evt) -> e=>console.log(e);