The WebAssembly.Table()
constructor creates a new
Table
object of the given size and element type.
Syntax
new WebAssembly.Table(tableDescriptor);
Parameters
- tableDescriptor
- An object that can contain the following members:
- element
- 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). - initial
- The initial number of elements of the WebAssembly Table.
- maximum Optional
- The maximum number of elements the WebAssembly Table is allowed to grow to.
Exceptions
- If
tableDescriptor
is not of type object, aTypeError
is thrown. - If
maximum
is specified and is smaller thaninitial
, aRangeError
is thrown.
Examples
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: {
tbl:tbl
}
};
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) {
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 compatibility
BCD tables only load in the browser