How to use javascript variable in Web worker thread

Question

I need to update my javascript array in Web worker thread. I cannot accces my javascript array in Web worker thread.

My code is :

self.onmessage = function(event) {
var array = new Uint8Array(event.data);
var sum = 0;
var temparray = new Array();

for(var list = 0; list < array.length; list++ ){
    var temp = myMethod(array[list]); //some operation
    availableArray.push(temp);
}

 self.postMessage("success");
}

I am getting this error: availableArrayis undefined availableArray.push(temp);

looks like you didn't declare availableArray, is there a availableArrays = [] somewhere? — lelloman
– lelloman, Commented Jun 23, 2014 at 10:28
Yes I defined availableArray in some other js file which already doing some operation. I need to update that array from worker thread. — Prasath
– Prasath, Commented Jun 24, 2014 at 3:28

Elias Van Ootegem · Accepted Answer · 2014-06-23 10:30:25Z

1

You define 2 variables that are arrays (or array-like objects): var array = new Uint8Array and var temparray = new Array, but then in the loop you use a variable that isn't declared anywhere availableArray, I suspect you want to change that variable to temparray.
The error message makes perfect sense: availableArray is not defined anywhere. You're using it as an array, and invoking the push method on it. However, JS, by default, creates a new variable for you whenever you use a var that hasn't been declared. The default value for a non-initialized variable is, of course, undefined. undefined doesn't have a push method, hence the error.

However, just a slight remark, though: in JS new Array is actually discouraged. Best use the array literal notation:

var temparray = [];

It's shorter and safer.

answered Jun 23, 2014 at 10:30

Elias Van Ootegem

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2 Comments

Prasath Over a year ago

But I defined availableArray in some other js file. I need to update that array from my worker thread. Is this possible to update an array or any variable which already doing some operation?

Elias Van Ootegem Over a year ago

@Prasath: A worker isn't a pure thread as you'd have in C/C++. It does not share state, but runs completely separate from the main JS thread. If you want to update the availableArray, you'll have to send a message to the main JS process, and update the data there

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