babel-plugin-debug-tools

babel-debug-tools

Babeljs Debug Tools helps you insert debug code and easely remove it when deploy to production

LOG

Similar to console.log but logs also identifiers and source code position

// app.js
function sum(a,b) {
  H5.LOG(a,b);
  → console.log('app.js:2:3', 'a='+ a, 'b='+ b);
  return a+b;
}

ASSERT

Similar to assert but logs also identifier and source code position

// app.js
function sum(a,b) {
  H5.ASSERT(a>0,b>0)
  → console.log('app.js:2:3', 'a='+ a, 'b='+ b); 
  → if (!(a>0)) throw new Error('assert a>0');
  → if (!(b>0)) throw new Error('assert b>0');
  return a+b
}

TRACE and CHECK

Useful for test local variables on test units. It's not for production mode.

// lib.js
function quadraticEquation(a,b,c) {
  const delta = b*b - 4*a*c; ← b² – 4ac
  H5.TRACE(a, b, c, delta)
  → tracelog.push('a=' +a + ' b=' + b +' c=' + c + ' delta=' + delta);
  if (delta<0) return null
  const x1 = (-b + sqrt(delta)) / (2*a)
  const x2 = (-b - sqrt(delta)) / (2*a)
  return {x1, x2}
}
// test.js
it(()=>{
  H5.TRACE() 
  → tracelog = [] // traceLog is a global
  const result = quadraticEquation(1, 8, -9) // x² + 8x - 9 = 0
  const deltaWasTraced = H5.CHECK(/delta=100/} 
  → const deltaWasTraced = traceLog.some(l=>/delta=100/.test(l)))
  except(deltaWasTraced).toBe(true)
  ...
})

Install

Using npm:

npm install --save-dev babel-debug-tools

Setup

babel.config.js:

module.exports = {
  plugins: [
      [
        require.resolve('babel-plugin-debug-tools'),
        {
          mode: 'DEV',
          identifier: 'H5'
        }
      ]
    ]
  ]
}

mode

Define plugin transform mode

• development or test - activate tools, this is default mode.
• production - remove debug tools from output

identifier

name of identifier for use tools, default is H5

define global

It's important defines the global on application boot

H5.INIT(() => {
  let traceLog;
  const H5 = {
    LOG(loc, ...args) {
      console.log(formatLoc(loc), ...args);
    },
    ASSERT(loc, ...args) {
      args.forEach((arg) => {
        if (!args[arg]) throw new Error(formatLoc(loc), arg);
      });
    },
    TRACE(...args) {
      if (args.length) 
        traceLog.push(args.join(' '));
      else
        traceLog = [];
    },
    CHECK(regExp) {
      return traceLog.some(l=>regExp.test(l)))
    }
  }
  if (typeof window !== 'undefined') window.H5 = H5;
  if (typeof global !== 'undefined') global.H5 = H5;
  function formatLoc(loc) {
    return (loc.filename || '') + ':' + loc.line + ':' + loc.column + ' ';
  }
});