WebAssembly.Table()

tableDescriptor

该对象具有以下属性：

element

一个表明储存在该 Table 中对象的类型。目前只能是： "anyfunc" (函数)。

initial

该 WebAssembly Table 初始大小。

maximum 可选

该 WebAssembly Table 允许扩展到的最大大小。

• 如果 tableDescriptor 不是对象类型，将会抛出 TypeError 异常。
• 如果申明了 maximum 属性并且比 initial 小，将会抛出 RangeError 异常。

所有Table实例都继承自Table()构造函数的原型对象 (en-US)-可以对其进行修改以影响所有Table实例。

Table.prototype.constructor

返回创建该对象实例的函数。默认情况下，这是WebAssembly.Table() 的构造函数。

Table.prototype.length (en-US)

返回 Table 的长度，即元素数。

Table.prototype.get() (en-US)

Accessor function — gets the element stored at a given index.

Table.prototype.grow() (en-US)

Increases the size of the Table instance by a specified number of elements.

Table.prototype.set() (en-US)

Sets an element stored at a given index to a given value.

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() (en-US) 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.

• WebAssembly overview page
• WebAssembly concepts
• Using the WebAssembly JavaScript API