WebAssembly.Table() constructor

The WebAssembly.Table() constructor creates a new Table object of the given size and element type.


new WebAssembly.Table(tableDescriptor);


An object that can contain the following members:
A string representing the type of value to be stored in the table. At the moment this can only have a value of "anyfunc" (functions).
The initial number of elements of the WebAssembly Table.
maximum Optional
The maximum number of elements the WebAssembly Table is allowed to grow to.


  • If tableDescriptor is not of type object, a TypeError is thrown.
  • If maximum is specified and is smaller than initial, a RangeError is thrown.


Creating a new WebAssembly Table instance

The following example (see table2.html source code and live version) creates a new WebAssembly Table instance with an initial size of 2 elements. 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 both elements are null.

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

We then create an import object that contains the table:

var importObj = {
  js: {

Finally, we load and instantiate a wasm module (table2.wasm) using the WebAssembly.instantiateStreaming() method.  The table2.wasm module contains two functions (one that returns 42 and another that returns 83) and stores both into elements 0 and 1 of the imported table (see text representation).  So after instantiation, the table still has length 2, but the elements now contain callable Exported WebAssembly Functions which we can call from JS.

WebAssembly.instantiateStreaming(fetch('table2.wasm'), importObject)
.then(function(obj) {

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.


WebAssembly JavaScript Interface
The definition of 'Table' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
Table() constructorChrome Full support 57Edge Full support 16Firefox Full support 52
Full support 52
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
IE No support NoOpera Full support 44Safari Full support 11WebView Android Full support 57Chrome Android Full support 57Firefox Android Full support 52
Full support 52
Notes Disabled in the Firefox 52 Extended Support Release (ESR).
Opera Android Full support 43Safari iOS Full support 11Samsung Internet Android Full support 7.0nodejs Full support 8.0.0


Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.

See also