> ## Documentation Index
> Fetch the complete documentation index at: https://docs.js-confuser.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Locks

> Customize the lock algorithm to your own implementation.

* Option name: `"lock.customLocks"`

* Option values: `true/false/0-1`

***

### Input / Output

This example showcases how `Custom Locks` transforms the code. Try it out by changing the input code and see changes apply in real-time.

```js title="Input.js" lines interactive-mode="obfuscate" theme={null}
// Input.js
function countermeasures() {
  throw new Error('Invalid browser!');
}
console.log('This only runs in Chrome!');

// Output.js
function FGbv92() {
  return navigator.userAgent.includes('Chrome');
}
if (!FGbv92()) {
  rYZeO0();
}
var f88D9Y = !1;
function rYZeO0() {
  if (f88D9Y) return;
  f88D9Y = !0;
  RnFxzK0();
}
function RnFxzK0() {
  function f88D9Y() {
    return navigator.userAgent.includes('Chrome');
  }
  if (!f88D9Y()) {
    rYZeO0();
  }
  throw new Error('Invalid browser!');
}
console.log('This only runs in Chrome!');
```

***

### Custom Locks API

Custom Locks allow you to define your own lock algorithm. These locks will be randomly sprinkled throughout the code.

The properties of the type `Custom Lock` are:

| Property             | Type     | Description                                                      |
| -------------------- | -------- | ---------------------------------------------------------------- |
| `code`               | `string` | Template lock code that must contain '{countermeasures}'.        |
| `percentagePerBlock` | `number` | The percentage of blocks that will contain the lock.             |
| `maxCount`           | `number` | The maximum number of times the lock can be used. (Default = 25) |
| `minCount`           | `number` | The minimum number of times the lock can be used. (Default = 1)  |

***

### Usage Example

The provided code example will obfuscate the file `input.js` and write the output to a file named `output.js`.

```js title="Usage Example" lines theme={null}
import JSConfuser from "js-confuser";
import {readFileSync, writeFileSync} from "fs";

// Read input code
const sourceCode = readFileSync("input.js", "utf8");
const options = {
  target: 'browser',
  lock: {
    countermeasures: 'countermeasures',
    customLocks: [
      {
        code: `
              function checkChrome(){
                return navigator.userAgent.includes("Chrome")
              }

              if(!checkChrome()){
                {countermeasures}
              }
              `,
        percentagePerBlock: 0.5,
        maxCount: 25,
        minCount: 1,
      },
    ],
  },
};

JSConfuser.obfuscate(sourceCode, options).then((result)=>{
  // Write output code
  writeFileSync("output.js", result.code);
}).catch(err=>{
  // Error occurred
  console.error(err);  
});
```

***

#### Enabled In

* [High Preset](/presets/high): No
* [Medium Preset](/presets/medium): No
* [Low Preset](/presets/low): No

***

#### See Also

* [Countermeasures](/options/countermeasures)