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WebAssembly.table.set

The set() prototype method of the WebAssembly.Table object mutates a reference stored at a given index to a different value.

Syntax

table.set(index, value);

Parameters

index
The index of the function reference you want to mutate.
value
The value you want to mutate the reference to. This must be an exported WebAssembly function, a JavaScript wrapper for an underlying wasm function.

Return value

Void.

Exceptions

Examples

Using Table.set

The following example (see table2.html source code and live version) creates a new WebAssembly Table instance with an initial size of 2 references. We then print out the table length and contents of the two indexes (retrieved via Table.prototype.get()) to show that the length is two, and the indexes currently contain no function references (they currently return null).

var tbl = new WebAssembly.Table({initial:2, element:"anyfunc"});
console.log(tbl.length);
console.log(tbl.get(0));
console.log(tbl.get(1));

We then create an import object that contains a reference to the table:

var importObj = {
  js: {
    tbl:tbl
  }
};

Finally, we load and instantiate a wasm module (table2.wasm) using the WebAssembly.instantiateStreaming(), log the table length, and invoke the two referenced functions that are now stored in the table (the table2.wasm module (see text representation) adds two function references to the table, both of which print out a simple value):

WebAssembly.instantiateStreaming(fetch('table2.wasm'), importObject)
.then(function(obj) {
  console.log(tbl.length);
  console.log(tbl.get(0)());
  console.log(tbl.get(1)());
});

Note how you've got to include a second function invocation operator at the end of the accessor to actually invoke the referenced function and log the value stored inside it (e.g. get(0)() rather than get(0)) .

This example shows that we're creating and accessing the table from JavaScript, but the same table is visible and callable inside the wasm instance too.

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
set 57 16 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
No 44 11
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
set 57 57 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
43 11 7.0
Server
Node.js
set 8.0.0

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/Table/set