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[pve-eslint.git] / eslint / docs / src / rules / global-require.md

---
title: global-require
rule_type: suggestion
---


This rule was **deprecated** in ESLint v7.0.0. Please use the corresponding rule in [`eslint-plugin-n`](https://github.com/eslint-community/eslint-plugin-n).

In Node.js, module dependencies are included using the `require()` function, such as:

```js
var fs = require("fs");
```

While `require()` may be called anywhere in code, some style guides prescribe that it should be called only in the top level of a module to make it easier to identify dependencies. For instance, it's arguably harder to identify dependencies when they are deeply nested inside of functions and other statements:

```js
function foo() {
    if (condition) {
        var fs = require("fs");
    }
}
```

Since `require()` does a synchronous load, it can cause performance problems when used in other locations.

Further, ES6 modules mandate that `import` and `export` statements can only occur in the top level of the module's body.

## Rule Details

This rule requires all calls to `require()` to be at the top level of the module, similar to ES6 `import` and `export` statements, which also can occur only at the top level.

Examples of **incorrect** code for this rule:

::: incorrect

```js
/*eslint global-require: "error"*/
/*eslint-env es6*/

// calling require() inside of a function is not allowed
function readFile(filename, callback) {
    var fs = require("fs");
    fs.readFile(filename, callback);
}

// conditional requires like this are also not allowed
if (DEBUG) {
    require("debug");
}

// a require() in a switch statement is also flagged
switch (x) {
    case "1":
        require("1");
        break;
}

// you may not require() inside an arrow function body
var getModule = (name) => require(name);

// you may not require() inside of a function body as well
function getModule(name) {
    return require(name);
}

// you may not require() inside of a try/catch block
try {
    require(unsafeModule);
} catch (e) {
    console.log(e);
}
```

:::

Examples of **correct** code for this rule:

::: correct

```js
/*eslint global-require: "error"*/

// all these variations of require() are ok
require("x");
var y = require("y");
var z;
z = require("z").initialize();

// requiring a module and using it in a function is ok
var fs = require("fs");
function readFile(filename, callback) {
    fs.readFile(filename, callback);
}

// you can use a ternary to determine which module to require
var logger = DEBUG ? require("dev-logger") : require("logger");

// if you want you can require() at the end of your module
function doSomethingA() {}
function doSomethingB() {}
var x = require("x"),
    z = require("z");
```

:::

## When Not To Use It

If you have a module that must be initialized with information that comes from the file-system or if a module is only used in very rare situations and will cause significant overhead to load it may make sense to disable the rule. If you need to `require()` an optional dependency inside of a `try`/`catch`, you can disable this rule for just that dependency using the `// eslint-disable-line global-require` comment.