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Better invariant / warning replacement

This commit is contained in:
Paul O’Shannessy 2015-05-21 19:08:18 -07:00
parent 5bee4a5e29
commit 02f1626725
2 changed files with 65 additions and 13 deletions
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2
package.json
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@ -67,7 +67,7 @@
},
"preferGlobal": true,
"commonerConfig": {
"version": 6
"version": 7
},
"scripts": {
"test": "jest",

76
vendor/constants.js vendored
View File

@ -37,21 +37,73 @@ module.exports = function(babel) {
CallExpression: {
exit: function(node, parent) {
if (this.get('callee').isIdentifier({name: 'invariant'})) {
// Truncate the arguments of invariant(condition, ...)
// statements to just the condition based on NODE_ENV
// (dead code removal will remove the extra bytes).
return t.conditionalExpression(
DEV_EXPRESSION,
node,
t.callExpression(node.callee, [node.arguments[0]])
// Turns this code:
//
// invariant(condition, argument, argument);
//
// into this:
//
// if (!condition) {
// if ("production" !== process.env.NODE_ENV) {
// invariant(false, argument, argument);
// } else {
// invariant(false);
// }
// }
//
// Specifically this does 2 things:
// 1. Checks the condition first, preventing an extra function call.
// 2. Adds an environment check so that verbose error messages aren't
// shipped to production.
// The generated code is longer than the original code but will dead
// code removal in a minifier will strip that out.
var condition = node.arguments[0];
return t.ifStatement(
t.unaryExpression('!', condition),
t.blockStatement([
t.ifStatement(
DEV_EXPRESSION,
t.blockStatement([
t.expressionStatement(
t.callExpression(
node.callee,
[t.literal(false)].concat(node.arguments.slice(1))
)
)
]),
t.blockStatement([
t.expressionStatement(
t.callExpression(
node.callee,
[t.literal(false)]
)
)
])
)
])
);
} else if (this.get('callee').isIdentifier({name: 'warning'})) {
// Eliminate warning(condition, ...) statements based on NODE_ENV
// (dead code removal will remove the extra bytes).
return t.conditionalExpression(
// Turns this code:
//
// warning(condition, argument, argument);
//
// into this:
//
// if ("production" !== process.env.NODE_ENV) {
// warning(condition, argument, argument);
// }
//
// The goal is to strip out warning calls entirely in production. We
// don't need the same optimizations for conditions that we use for
// invariant because we don't care about an extra call in __DEV__
return t.ifStatement(
DEV_EXPRESSION,
node,
t.literal(null)
t.blockStatement([
t.expressionStatement(
node
)
])
);
}
}