hello_world_bg.js

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/* tslint:disable */
import * as wasm from './hello_world_bg';

const TextDecoder = typeof self === 'object' && self.TextDecoder
    ? self.TextDecoder
    : require('util').TextDecoder;

let cachedDecoder = new TextDecoder('utf-8');

let cachedUint8Memory = null;
function getUint8Memory() {
    if (cachedUint8Memory === null ||
        cachedUint8Memory.buffer !== wasm.memory.buffer)
        cachedUint8Memory = new Uint8Array(wasm.memory.buffer);
    return cachedUint8Memory;
}

function getStringFromWasm(ptr, len) {
    return cachedDecoder.decode(getUint8Memory().slice(ptr, ptr + len));
}

let cachedUint32Memory = null;
function getUint32Memory() {
    if (cachedUint32Memory === null ||
        cachedUint32Memory.buffer !== wasm.memory.buffer)
        cachedUint32Memory = new Uint32Array(wasm.memory.buffer);
    return cachedUint32Memory;
}

let cachedGlobalArgumentPtr = null;
function globalArgumentPtr() {
    if (cachedGlobalArgumentPtr === null)
        cachedGlobalArgumentPtr = wasm.__wbindgen_global_argument_ptr();
    return cachedGlobalArgumentPtr;
}

function getGlobalArgument(arg) {
    const idx = globalArgumentPtr() / 4 + arg;
    return getUint32Memory()[idx];
}

export function generate_greeting() {
    const ret = wasm.generate_greeting();
    const len = getGlobalArgument(0);
    const realRet = getStringFromWasm(ret, len);
    wasm.__wbindgen_free(ret, len * 1);
    return realRet;
}

const TextEncoder = typeof self === 'object' && self.TextEncoder
    ? self.TextEncoder
    : require('util').TextEncoder;

let cachedEncoder = new TextEncoder('utf-8');

function passStringToWasm(arg) {

    const buf = cachedEncoder.encode(arg);
    const ptr = wasm.__wbindgen_malloc(buf.length);
    getUint8Memory().set(buf, ptr);
    return [ptr, buf.length];
}

function setGlobalArgument(arg, i) {
    const idx = globalArgumentPtr() / 4 + i;
    getUint32Memory()[idx] = arg;
}

export function generate_custom_greeting(arg0) {
    const [ptr0, len0] = passStringToWasm(arg0);
    setGlobalArgument(len0, 0);
    try {
        const ret = wasm.generate_custom_greeting(ptr0);
        const len = getGlobalArgument(0);
        const realRet = getStringFromWasm(ret, len);
        wasm.__wbindgen_free(ret, len * 1);
        return realRet;
    } finally {
        wasm.__wbindgen_free(ptr0, len0 * 1);
    }
}

export function __wbindgen_throw(ptr, len) {
    throw new Error(getStringFromWasm(ptr, len));
}

There is quite a bit going on here.

The key piece is that our two functions are defined in this file, generate_greeting and generate_custom_greeting. The rest is a series of helper functions to make working with the js/wasm memory a little easier. Now lets go over how we might use this and our .wasm files.

If you want to dig a little further, I have tried to summarize each function definition.