1# @ohos.hiviewdfx.jsLeakWatcher (JSLeakWatcher)
2
3This module provides the capability of monitoring whether JS objects are leaked.
4
5> **NOTE**
6>
7> The initial APIs of this module are supported since API version 12. Newly added APIs will be marked with a superscript to indicate their earliest API version.
8
9## Modules to Import
10
11```js
12import { jsLeakWatcher } from '@kit.PerformanceAnalysisKit';
13```
14
15
16## jsLeakWatcher.enable
17
18enable(isEnable: boolean): void;
19
20Enables the detection for JS object leak. This function is disabled by default.
21
22**System capability**: SystemCapability.HiviewDFX.HiChecker
23
24**Parameters**
25
26| Name | Type | Mandatory | Description |
27| -------- | -------- | -------- | -------- |
28| isEnable | boolean | Yes | Indicates whether to enable **jsLeakWatcher**. |
29
30**Example**
31
32```js
33jsLeakWatcher.enable(true);
34```
35
36
37## jsLeakWatcher.watch
38
39watch(obj: object, msg: string): void;
40
41Registers the object to be checked.
42
43**System capability**: SystemCapability.HiviewDFX.HiChecker
44
45**Parameters**
46
47| Parameter | Type | Mandatory | Description |
48| -------- | -------- | -------- | -------- |
49| obj | object | Yes | Name of the object to be checked. |
50| msg | string | Yes | User-defined object information. |
51
52**Example**
53
54```js
55let obj:Object = new Object();
56jsLeakWatcher.watch(obj, "Trace Object");
57```
58
59
60## jsLeakWatcher.check
61
62check(): string;
63
64Obtains the list of objects that are registered using **jsLeakWatcher.watch()** and may leak. Objects that are not reclaimed after GC is triggered are marked as leaked.
65
66**System capability**: SystemCapability.HiviewDFX.HiChecker
67
68**Return value**
69
70| Type   | Description                                                      |
71| ------- | ---------------------------------------------------------- |
72| string | List of objects that are suspected to leak, in JSON format. |
73
74**Example**
75```js
76let leakObjlist:string = jsLeakWatcher.check();
77```
78
79
80## jsLeakWatcher.dump
81
82dump(filePath: string): Array<string>;
83
84Exports the list of leaked objects and VM memory snapshot.
85
86**System capability**: SystemCapability.HiviewDFX.HiChecker
87
88**Parameters**
89
90| Parameter | Type | Mandatory | Description |
91| -------- | -------- | -------- | -------- |
92| filePath | string | Yes | The path for storing exported information files. |
93
94**Return value**
95
96| Type   | Description                                                      |
97| ------- | ---------------------------------------------------------- |
98| Array<string> | Array of exported results. Index **0** indicates the name of the leak list file, and the file name extension is **.jsleaklist**. Index **1** indicates the name of the VM memory snapshot file, and the file name extension is **.heapsnapshort**. |
99
100**Example**
101
102```js
103let context = getContext(this);
104let files:Array<string> = jsLeakWatcher.dump(context.filesDir);
105```
106