Playing with ASTs (Babelv6)

readme.md

Add the line and column as the first argument on every console.log call.

plugin.js

export default function(babel) {
  const { types: t } = babel;

  return {
    name: "consoleImproved",
    visitor: {
      CallExpression(path) {
        if (path.node.callee.object && path.node.callee.object.name === "console") {
          const parentFunction = path.findParent(t.isFunctionDeclaration);
          const parentFunctionExpression = path.findParent(t.isFunctionExpression);
          const parentArrowFunction = path.findParent(t.isArrowFunctionExpression);
          const startConsole = path.node.loc.start;
          let helperMessage = `${startConsole.line}:${startConsole.column}`;
          if (parentFunction) {
            helperMessage = `${parentFunction.node.id.name} ${helperMessage}`;
          } else if (parentArrowFunction) {
            helperMessage = `${parentArrowFunction.parent.id.name} ${helperMessage}`;
          } else if (parentFunctionExpression) {
            helperMessage = `${parentFunctionExpression.parent.id.name} ${helperMessage}`;
          }
          path.node.arguments.unshift(t.stringLiteral(helperMessage));
        }
      }
    }
  };
}

result.js

function add(a, b) {
  console.log("add 2:2", a, b)
  return a + b
}

function subtract(a, b) {
  console.log("subtract 7:2", a, b)
  return a - b
}

const multiply = (a, b) => {
  console.log("multiply 12:2", a, b)
  return a * b
}

const divide = function(a, b) {
  console.log("divide 17:2", a, b)
  return a / b
}

add(1, 2)
subtract(2, 1)
multiply(3, 4)
divide(25, 5)
console.log("25:0", 'sup dawg')

testfile.js

function add(a, b) {
  console.log(a, b)
  return a + b
}

function subtract(a, b) {
  console.log(a, b)
  return a - b
}

const multiply = (a, b) => {
  console.log(a, b)
  return a * b
}

const divide = function(a, b) {
  console.log(a, b)
  return a / b
}

add(1, 2)
subtract(2, 1)
multiply(3, 4)
divide(25, 5)
console.log('sup dawg')