脚本引擎

介绍

脚本引擎分两个版本，js1.0, js2.0,通过系统参数：bingo.script.use.js2.0来进行切换。两个版本脚本引擎差异如下：

语言特性支持

特性项	js1.0	js2.0	说明
ES标准支持情况	ES5.1, 部分ES6特性	ES2022
模块支持情况	commonjs	es module/commonjs	通过系统参数bingo.js2.script.module控制
异步支持（Promise/async/await)	N	Y
setTimeout, clearTimeout	N	Y
ES6 class support	Y	Y
Proxy	Y	Y
Symbol	Y	Y
Map, Set, WeakMap, WeakSet	Y	Y
Typed Arrays	Y	Y
for-of	Y	Y
Reflect	Y	Y
Block-scoped declarations (let and const)	Y	Y
Optional catch binding	Y	Y
Destructuring assignments	Y	Y
Default function parameters	Y	Y
Spread and rest properties	Y	Y
Arrow functions	Y	Y
Template literals	Y	Y
Optional chaining	Y	Y
** Operator	Y	Y
Nullish Coalescing Operator	Y	Y
generators	Y	Y
String.prototype.replaceAll	Y	Y

js1.0/js2.0均不兼容npm生态。

性能差异

js2.0性能远远优于js1.0, 大部分场景下，性能提升了100%~1000%, 如JSON.parse提升了800%, JSON.stringify提升了500%。

js2.0新增加API

因为js2.0支持异步，所以新增加部分异步api:

• setTimeout
• clearTimeout
• db.sql.executeAsync

import * as db from 'db';

function bad() {
    let p = db.sql().executeAsync("select * from m__wasm__cst limit 1", { dynamic: false });
    p.then((value) => {
        console.log(value);
    }).catch((reason) => {
        console.log("execption = ", reason);
    });
}

function ok() {
    let p = db.sql().executeAsync("select * from m__wasm__cst limit 1", { dynamic: true });
    p.then((value) => {
        console.log("affected rows = ", value.AffectedRows);
    }).catch((reason) => {
        console.log("execption = ", reason);
    });
}

console.log("hello 1");
setTimeout(ok, "1000");
console.log("hello 2");
setTimeout(bad, "100");
console.log("hello 3");

输出：

0703 15:27:00.626|debug|vm[1]>>> hello 1 (m__obs:18)
0703 15:27:00.626|debug|vm[1]>>> hello 2 (m__obs:20)
0703 15:27:00.626|debug|vm[1]>>> hello 3 (m__obs:22)
0703 15:27:01.631|debug|vm[1]>>> affected rows =  1 (m__obs:13)
0703 15:27:01.631|debug|vm[1]>>> execption =  Error 
{
    message: "object m__wasm__cst is used but not decorated with @useObject, please decorate it first."
} (m__obs:7)

• http.client.requestAsync

import * as http from 'http';
import * as context from 'context';

const option: http.ClientOption = {
    baseUrl: context.getHost() + "/u-route/baas/"
}
const headers = {
    "access-token": context.getToken(),
    "content-type": "application/json",
};

const client = http.newClient(option);
let p = client.requestAsync(http.Method.GET, "script/v1.0/declaration", { headers: headers });

p.then((resp) => {
    console.log(`resp length is `, len(resp.body.result));
}).catch((reason) => {
    console.log(`error is `, reason);
});

console.log("hello, here");

输出：

0712 16:46:57.832|debug|vm[68]>>> hello, here (m__httpdemo:19)
0712 16:46:57.832|debug|vm[68]>>> resp length is  2 (m__httpdemo:15)

动态加载模块

commonjs的require函数，esmodule的import函数。

commonjs:

const res = require('./m__util');
res.sayHello('common js dynamic import');

esmodule:

import('./m__util').then((res) => {
    res.sayHello("es module dynamic import");
});

兼容性差异

部分AppCube封装api有些差异：

Decimal类型Exponent方法在某些场景计算结果不同

import * as decimal from 'decimal';

let d1 = decimal.newFromString('-123.4567');
let d2 = decimal.newFromString('-321.231');
let avg = decimal.avg(d1, d2);
console.log("avg :  ", avg);
console.log("avg exponent :  ", avg.Exponent());

js1.0输出结果

617 19:38:03.685|debug|vm[12]>>> avg :   -222.34385 (m__avgdecimal.ts:6:12(36))
0617 19:38:03.685|debug|vm[12]>>> avg exponent :   -16 (m__avgdecimal.ts:7:12(44))

js2.0输出结果:

0617 19:35:29.125|debug|vm[11]>>> avg :   -222.34385 (m__avgdecimal:5)
0617 19:35:29.125|debug|vm[11]>>> avg exponent :   -5 (m__avgdecimal:6)

从输出结果来看，js2.0输出结果更加符合我们的直觉。