react/scripts/babel/wrap-warning-with-env-check.js

65 lines
1.7 KiB
JavaScript

/**
* Copyright (c) 2013-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
'use strict';
module.exports = function(babel, options) {
const t = babel.types;
const DEV_EXPRESSION = t.identifier('__DEV__');
const SEEN_SYMBOL = Symbol('expression.seen');
return {
visitor: {
CallExpression: {
exit: function(path) {
const node = path.node;
// Ignore if it's already been processed
if (node[SEEN_SYMBOL]) {
return;
}
if (path.get('callee').isIdentifier({name: 'warning'})) {
// Turns this code:
//
// warning(condition, argument, argument);
//
// into this:
//
// if (__DEV__) {
// if (!condition) {
// warning(false, argument, argument);
// }
// }
//
// The goal is to strip out warning calls entirely in production
// and to avoid evaluating the arguments in development.
const condition = node.arguments[0];
const newNode = t.callExpression(
node.callee,
[t.booleanLiteral(false)].concat(node.arguments.slice(1))
);
newNode[SEEN_SYMBOL] = true;
path.replaceWith(
t.ifStatement(
DEV_EXPRESSION,
t.blockStatement([
t.ifStatement(
t.unaryExpression('!', condition),
t.expressionStatement(newNode)
),
])
)
);
}
},
},
},
};
};