Console
The console module provides a simple debugging console, which is similar to the JavaScript console provided by the browser.
NOTE
The initial APIs of this module are supported since API version 3. Newly added APIs will be marked with a superscript to indicate their earliest API version.
console.debug
debug(message: string, ...arguments: any[]): void
Prints debugging information in formatted output mode.
Since API version 9, this API is supported in ArkTS widgets.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| message | string | Yes | Text to be printed. |
| arguments | any[] | No | Arguments in the message or other information to be printed. |
Example
const number = 5;
console.debug('count: %d', number); // Print the debugging information with arguments in the message replaced.
// count: 5
console.debug('count:', number); // Print the message and other information.
// count: 5
console.debug('count:'); // Print the message only.
// count:
console.log
log(message: string, ...arguments: any[]): void
Prints log information in formatted output mode.
Since API version 9, this API is supported in ArkTS widgets.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| message | string | Yes | Text to be printed. |
| arguments | any[] | No | Arguments in the message or other information to be printed. |
Example
const number = 5;
console.log('count: %d', number); // Print the log information with arguments in the message replaced.
// count: 5
console.log('count:', number); // Print the message and other information.
// count: 5
console.log('count:'); // Print the message only.
// count:
console.info
info(message: string, ...arguments: any[]): void
Prints log information in formatted output mode. This API is the alias of console.log ().
Since API version 9, this API is supported in ArkTS widgets.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| message | string | Yes | Text to be printed. |
| arguments | any[] | No | Arguments in the message or other information to be printed. |
Example
const number = 5;
console.info('count: %d', number); // Print the log information with arguments in the message replaced.
// count: 5
console.info('count:', number); // Print the message and other information.
// count: 5
console.info('count:'); // Print the message only.
// count:
console.warn
warn(message: string, ...arguments: any[]): void
Prints warning information in formatted output mode.
Since API version 9, this API is supported in ArkTS widgets.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| message | string | Yes | Warning information to be printed. |
| arguments | any[] | No | Arguments in the message or other information to be printed. |
Example
const str = "name should be string";
console.warn('warn: %d', str); // Print the warning information with arguments in the message replaced.
// warn: name should be string
console.warn('warn:', str); // Print the message and other information.
// warn: name should be string
console.warn('warn:'); // Print the message only.
// warn:
console.error
error(message: string, ...arguments: any[]): void
Prints error information in formatted output mode.
Since API version 9, this API is supported in ArkTS widgets.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| message | string | Yes | Error information to be printed. |
| arguments | any[] | No | Arguments in the message or other information to be printed. |
Example
const str = "value is not defined";
console.error('error: %d', str); // Print the error information with arguments in the message replaced.
// error: value is not defined
console.error('error:', str); // Print the message and other information.
// error: value is not defined
console.error('error:'); // Print the message only.
// error:
console.assert10+
assert(value?: Object, ...arguments: Object[]): void
Prints assertion information.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| value | Object | No | Result value. If value is false or left blank, the output starting with "Assertion failed" is printed. If value is true, no information is printed. |
| arguments | Object | No | Other information to be printed when value is false. If this parameter is left blank, other information is not printed. |
Example
console.assert(true, 'does nothing'); // Do not print error information as value is true.
console.assert(2% 1 == 0,'does nothing'); // Do not print error information as value is true.
console.assert(false, 'console %s work', 'didn\'t');
// Assertion failed: console didn't work
console.assert();
// Assertion failed
console.count10+
count(label?: string): void
Maintains an internal counter. When this counter is invoked, its label name and the corresponding call count are printed.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| label | string | No | Counter label name. The default value is default. |
Example
console.count()
// default: 1
console.count('default')
// default: 2
console.count('abc')
// abc: 1
console.count('xyz')
// xyz: 1
console.count('abc')
// abc: 2
console.count()
// default: 3
console.countReset10+
countReset(label?: string): void
Resets a counter based on the specified label name.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| label | string | No | Counter label name. The default value is default. |
Example
console.count('abc');
// abc: 1
console.countReset('abc');
console.count('abc');
// abc: 1
console.dir10+
dir(dir?: Object): void
Prints content of the specified object.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| dir | Object | No | Object whose content needs to be printed. If this parameter is left blank, no information is printed. |
Example
class bar {
baz: boolean = true;
}
let b: bar = {baz: true}
class foo{
bar: bar = b;
}
let c: foo = {bar: b}
class c1{
foo: foo = c;
}
let a: c1 = {foo: c}
console.dir(a);
// Object: {"foo":{"bar":{"baz":true}}}
console.dir(); // No information is printed.
console.dirxml10+
dirxml(...arguments: Object[]): void
Displays an interactive tree of the descendant elements of the specified XML element. This API is implemented by calling console.log() internally. It does not produce any XML elements. The usage method is the same as that of console.log().
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| arguments | Object | Yes | Information to be printed. |
Example
const number = 5;
console.dirxml('count: %d', number);
// count: 5
console.dirxml('count:', number);
// count: 5
console.dirxml('count:');
// count:
console.group10+
group(...arguments: Object[]): void
Increases the indentation of subsequent lines by two spaces. If the information to be printed is provided, the information is printed without extra indentation.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| arguments | Object | No | Information to be printed. |
Example
console.log("outter");
// outter
console.group();
console.log("level 1");
// level 1
console.group("in level1");
// in level1
console.log("level 2");
// level 2
console.groupCollapsed10+
groupCollapsed(...arguments: Object[]): void
Creates a new inline group in collapsed mode. The usage and function of this API are the same as those of console.group().
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| arguments | Object | No | Information to be printed. |
Example
console.groupCollapsed("outter");
// outter
console.groupCollapsed();
console.log("level 1");
// level 1
console.groupCollapsed("in level1");
// in level1
console.log("level 2");
// level 2
console.groupEnd10+
groupEnd(): void
Reduces the indentation of subsequent lines by two spaces.
System capability: SystemCapability.Utils.Lang
Example
console.log("outter");
// outter
console.group();
console.log("level 1");
// level 1
console.groupEnd();
console.log("outter");
// outter
console.table10+
table(tableData?: Object): void
Prints data in a table.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| tableData | Object | No | Data to be printed in a table. If this parameter is left blank, no information is printed. |
Example
console.table([1, 2, 3]);
// ┌─────────┬────────┐
// │ (index) │ Values │
// ├─────────┼────────┤
// │ 0 │ 1 │
// │ 1 │ 2 │
// │ 2 │ 3 │
// └─────────┴────────┘
console.table({ a: [1, 2, 3, 4, 5], b: 5, c: { e: 5 } });
// ┌─────────┬───┬───┬───┬───┬───┬───┬────────┐
// │ (index) │ 0 │ 1 │ 2 │ 3 │ 4 │ e │ Values │
// ├─────────┼───┼───┼───┼───┼───┼───┼────────┤
// │ a │ 1 │ 2 │ 3 │ 4 │ 5 │ │ │
// │ b │ │ │ │ │ │ │ 5 │
// │ c │ │ │ │ │ │ 5 │ │
// └─────────┴───┴───┴───┴───┴───┴───┴────────┘
console.time10+
time(label?: string): void
Starts a timer to track the duration of an operation. You can use console.timeEnd() to close the timer and print the elapsed time (in ms).
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| label | string | No | Timer label. The default value is default. |
Example
console.time('abc');
console.timeEnd10+
timeEnd(label?: string): void
Stops the timer started by calling console.time() and prints the elapsed time (in ms).
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| label | string | No | Timer label. The default value is default. |
Example
console.time('abc');
console.timeEnd('abc');
// abc: 225.438ms
console.timeLog10+
timeLog(label?: string, ...arguments: Object[]): void
Prints the elapsed time and other data parameters for the timer started by console.time().
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| label | string | No | Timer label. The default value is default. |
| arguments | Object | No | Logs to be printed. |
Example
console.time('timer1');
console.timeLog('timer1', 17);
// timer1: 365.227ms 17
console.timeEnd('timer1');
// timer1: 513.22ms
console.trace10+
trace(...arguments: Object[]): void
Creates a stack trace.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| arguments | Object | No | Logs to be printed. If this parameter is left blank, only stack information is printed. |
Example
console.trace();
// Trace:
// xxxxxxxxxx (current stack information)
console.trace("Show the trace");
// Trace: Show the trace
// xxxxxxxxxx (current stack information)