Object FSWatcher

filesystem watch object

When the call fs.watch(target)succeeds , an object of this type is returned

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var fs = require("fs");
var watcher = fs.watch((eventType, filename) => {
    if (filename) {
        console.log(filename);
        // Prints: <Buffer ...>
    }
});

watcher.close();

// 带回调地调用
fs.watch('./tmp', {
    encoding: 'buffer'
}, (eventType, filename) => {
    if (filename) {
        console.log(filename);
        // Prints: <Buffer ...>
    }
});

inheritance relationship

static property

defaultMaxListeners

Integer, the default global maximum number of listeners

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static Integer FSWatcher.defaultMaxListeners;

member attribute

onchange

Function, query and bind "file change" event, equivalent to on("change", func);

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Function FSWatcher.onchange;

onclose

Function, query and bind the "watcher closed" event, equivalent to on("close", func);

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Function FSWatcher.onclose;

onerror

Function, query and bind the "error occurred" event, which is equivalent to on("error", func);

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Function FSWatcher.onerror;

member function

close

Close the Watcher and no longer receive corresponding file change processing events

1FSWatcher.close();

on

Bind an event handler to an object

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Object FSWatcher.on(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Bind an event handler to an object

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Object FSWatcher.on(Object map);

Call parameters:

map: Object, specify the event mapping relationship, the object attribute name will be used as the event name, and the attribute value will be used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

addListener

Bind an event handler to an object

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Object FSWatcher.addListener(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Bind an event handler to an object

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Object FSWatcher.addListener(Object map);

Call parameters:

map: Object, specify the event mapping relationship, the object attribute name will be used as the event name, and the attribute value will be used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

prependListener

Bind an event handler function to the object start

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Object FSWatcher.prependListener(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Bind an event handler function to the object start

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Object FSWatcher.prependListener(Object map);

Call parameters:

map: Object, specify the event mapping relationship, the object attribute name will be used as the event name, and the attribute value will be used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

once

Bind a one-time event handler to the object, the one-time handler will only be triggered once

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Object FSWatcher.once(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Bind a one-time event handler to the object, the one-time handler will only be triggered once

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Object FSWatcher.once(Object map);

Call parameters:

map: Object, specify the event mapping relationship, the object attribute name will be used as the event name, and the attribute value will be used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

prependOnceListener

Bind an event handler function to the object start

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Object FSWatcher.prependOnceListener(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Bind an event handler function to the object start

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Object FSWatcher.prependOnceListener(Object map);

Call parameters:

map: Object, specify the event mapping relationship, the object attribute name will be used as the event name, and the attribute value will be used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

off

unspecify function from object processing queue

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Object FSWatcher.off(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Cancels all functions in the object processing queue

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Object FSWatcher.off(String ev);

Call parameters:

ev: String, the name of the specified event

return result:

Object, returns the event object itself, which is convenient for chain calls

unspecify function from object processing queue

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Object FSWatcher.off(Object map);

Call parameters:

map: Object, specifies the event mapping relationship, the name of the object attribute is used as the event name, and the value of the attribute is used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

removeListener

unspecify function from object processing queue

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Object FSWatcher.removeListener(String ev,
    Function func);

Call parameters:

ev: String, the name of the specified event
func: Function, specifies the event handler function

return result:

Object, returns the event object itself, which is convenient for chain calls

Cancels all functions in the object processing queue

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Object FSWatcher.removeListener(String ev);

Call parameters:

ev: String, the name of the specified event

return result:

Object, returns the event object itself, which is convenient for chain calls

unspecify function from object processing queue

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Object FSWatcher.removeListener(Object map);

Call parameters:

map: Object, specifies the event mapping relationship, the name of the object attribute is used as the event name, and the value of the attribute is used as the event processing function

return result:

Object, returns the event object itself, which is convenient for chain calls

removeAllListeners

Cancels all listeners for all events from the object processing queue, or removes all listeners for the specified event if an event is specified.

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Object FSWatcher.removeAllListeners(String ev);

Call parameters:

ev: String, the name of the specified event

return result:

Object, returns the event object itself, which is convenient for chain calls

Cancels all listeners for all events from the object processing queue, or removes all listeners for the specified event if an event is specified.

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Object FSWatcher.removeAllListeners(Array evs = []);

Call parameters:

evs: Array, the name of the specified event

return result:

Object, returns the event object itself, which is convenient for chain calls

setMaxListeners

The default limit on the number of listeners, for compatibility only

1FSWatcher.setMaxListeners(Integer n);

Call parameters:

n: Integer, specifies the number of events

getMaxListeners

Gets the default limited number of listeners, for compatibility only

1Integer FSWatcher.getMaxListeners();

return result:

Integer, returns the default limit number

listeners

Query the array of listeners for the specified event of the object

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Array FSWatcher.listeners(String ev);

Call parameters:

ev: String, the name of the specified event

return result:

Array, returns an array of listeners for the specified event

listenerCount

Query the number of listeners for the specified event of the object

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Integer FSWatcher.listenerCount(String ev);

Call parameters:

ev: String, the name of the specified event

return result:

Integer, returns the number of listeners for the specified event

Query the number of listeners for the specified event of the object

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2Integer FSWatcher.listenerCount(Value o,
    String ev);

Call parameters:

o: Value, specifies the object of the query
ev: String, the name of the specified event

return result:

Integer, returns the number of listeners for the specified event

eventNames

Query listener event name

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Array FSWatcher.eventNames();

return result:

Array, returns an array of event names

emit

Actively trigger an event

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Boolean FSWatcher.emit(String ev,
    ...args);

Call parameters:

ev: String, event name
args: ..., event parameters, will be passed to the event handler function

return result:

Boolean, returns the event trigger status, returns true if there is a response event, otherwise returns false

toString

Return the string representation of the object, generally return "[Native Object]", the object can be reimplemented according to its own characteristics

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String FSWatcher.toString();

return result:

String, returns a string representation of the object

toJSON

Returns the JSON format representation of the object, generally returns a collection of readable properties defined by the object

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Value FSWatcher.toJSON(String key = "");

Call parameters:

key: String, not used

return result:

Value, which returns a JSON-serializable value

development guide

Basic module

built-in object

community module

Object FSWatcher

inheritance relationship

static property

defaultMaxListeners

member attribute

onchange

onclose

onerror

member function

close

on

addListener

prependListener

once

prependOnceListener

off

removeListener

removeAllListeners

setMaxListeners

getMaxListeners

listeners

listenerCount

eventNames

emit

toString

toJSON