Anna Henningsen d7452b7140 module: warn on using unfinished circular dependency ... Warn when a non-existent property of an unfinished module.exports object is being accessed, as that very often indicates the presence of a hard-to-detect and hard-to-debug problem. This mechanism is only used if `module.exports` is still a regular object at the point at which the second, circular `require()` happens. The downside is that, temporarily, `module.exports` will have a prototype other than `Object.prototype`, and that there may be valid uses of accessing non-existent properties of unfinished `module.exports` objects. Performance of circular require calls in general is not noticeably impacted. confidence improvement accuracy (*) (**) (***) module/module-loader-circular.js n=10000 3.96 % ±5.12% ±6.82% ±8.89% Example: $ cat a.js 'use strict'; const b = require('./b.js'); exports.fn = () => {}; $ cat b.js 'use strict'; const a = require('./a.js'); a.fn(); $ node a.js (node:1617) Warning: Accessing non-existent property 'fn' of module exports inside circular dependency /tmp/b.js:4 a.fn(); ^ TypeError: a.fn is not a function at Object.<anonymous> (/tmp/b.js:4:3) [...] PR-URL: https://github.com/nodejs/node/pull/29935 Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>		2019-11-01 19:58:41 +01:00
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module-loader-circular.js	module: warn on using unfinished circular dependency	2019-11-01 19:58:41 +01:00
module-loader-deep.js
module-loader.js