how to javascript websocket call a function in onmessage?

Question

    websocketstart()
    {
        exampleSocket = new WebSocket('ws://127.0.0.1:8000');
        exampleSocket.onopen = function() {
            // alert('handshake successfully established. May send data now...');
            // exampleSocket.send('hello!!!')
        };
        exampleSocket.onmessage = function(event) {
            let result = JSON.parse(event.data);
            if(result.error == false)
            {
                console.log("ERROR : " + result.parent.message);
                alert('error');
                return;
            }
            this.wantcallfunction(); //<---- SCRIPT438: Object doesn't support property or method 'wantcallfunction'
            return;
        };
        exampleSocket.onclose = function() {
            alert('connection closed');
        };
    }

    wantcallfunction()
    {

    }

this.wantcallfunction(); //<---- SCRIPT438: Object doesn't support property or method 'wantcallfunction'

Is there any other way to call the function from within onmessage?

charlietfl · Accepted Answer · 2018-11-20 02:48:31Z

7

Use arrow functions so you keep context of this as the class.

Change

exampleSocket.onmessage = function(event) {
    // `this` is not the class

To

exampleSocket.onmessage = (event) => {
    // `this` is  the class

edited Nov 20, 2018 at 2:48

answered Nov 20, 2018 at 2:43

charlietfl

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1 Comment

stiveaustin Over a year ago

It works well within the script. Just call function in another script in wantcallfunction (). mywebsockt.ts ㄴ wantcallfunction() -> [other.ts] othercallback() other.ts ㄴothercallback -> otherfunction() // <- SCRIPT5007: Unable to get property 'otherfunction' of undefined or null reference

stiveaustin · Accepted Answer · 2018-11-20 02:53:51Z

0

static instance : MySocketTest 

MySocketTest.instance = this;

exampleSocket.onmessage = function(event) {
MySocketTest.instance.wantcallfunction();

Resolved.

There is no error, but I do not know if this is correct.

edited Nov 20, 2018 at 2:53

answered Nov 20, 2018 at 2:47

stiveaustin

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