es5-compliance

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English

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Translation

Chinese

ES5 Compliance for ServiceNow

ServiceNow的ES5合规性

ServiceNow runs on Mozilla Rhino engine which only supports ES5 JavaScript (2009 standard). All server-side scripts MUST use ES5 syntax.

ServiceNow基于Mozilla Rhino引擎运行，该引擎仅支持ES5 JavaScript（2009标准）。所有服务器端脚本必须使用ES5语法。

Forbidden Syntax (WILL CAUSE SyntaxError)

禁止使用的语法（会导致SyntaxError）

ES6+ Syntax	ES5 Alternative
`const x = 5`	`var x = 5`
`let items = []`	`var items = []`
`() => {}`	`function() {}`
`Hello ${name}`	`'Hello ' + name`
`for (x of arr)`	`for (var i = 0; i < arr.length; i++)`
`{a, b} = obj`	`var a = obj.a; var b = obj.b;`
`[a, b] = arr`	`var a = arr[0]; var b = arr[1];`
`...spread`	Use `Array.prototype.slice.call()`
`class MyClass {}`	Use constructor functions
`async/await`	Use GlideRecord callbacks
`Promise`	Use GlideRecord with callbacks

ES6+语法	ES5替代方案
`const x = 5`	`var x = 5`
`let items = []`	`var items = []`
`() => {}`	`function() {}`
`Hello ${name}`	`'Hello ' + name`
`for (x of arr)`	`for (var i = 0; i < arr.length; i++)`
`{a, b} = obj`	`var a = obj.a; var b = obj.b;`
`[a, b] = arr`	`var a = arr[0]; var b = arr[1];`
`...spread`	使用 `Array.prototype.slice.call()`
`class MyClass {}`	使用构造函数
`async/await`	使用GlideRecord回调
`Promise`	使用GlideRecord回调

Common Patterns

常见模式

Variable Declarations

变量声明

javascript

// WRONG - ES6
const MAX_RETRIES = 3;
let currentUser = gs.getUser();

// CORRECT - ES5
var MAX_RETRIES = 3;
var currentUser = gs.getUser();

javascript

// 错误 - ES6
const MAX_RETRIES = 3;
let currentUser = gs.getUser();

// 正确 - ES5
var MAX_RETRIES = 3;
var currentUser = gs.getUser();

Functions

函数

javascript

// WRONG - Arrow functions
var active = incidents.filter(inc => inc.active);
var process = () => { return 'done'; };

// CORRECT - ES5 functions
var active = [];
for (var i = 0; i < incidents.length; i++) {
  if (incidents[i].active) {
    active.push(incidents[i]);
  }
}
var process = function() { return 'done'; };

javascript

// 错误 - 箭头函数
var active = incidents.filter(inc => inc.active);
var process = () => { return 'done'; };

// 正确 - ES5函数
var active = [];
for (var i = 0; i < incidents.length; i++) {
  if (incidents[i].active) {
    active.push(incidents[i]);
  }
}
var process = function() { return 'done'; };

String Concatenation

字符串拼接

javascript

// WRONG - Template literals
var message = `Incident ${number} assigned to ${user}`;

// CORRECT - String concatenation
var message = 'Incident ' + number + ' assigned to ' + user;

javascript

// 错误 - 模板字符串
var message = `Incident ${number} assigned to ${user}`;

// 正确 - 字符串拼接
var message = 'Incident ' + number + ' assigned to ' + user;

Loops

循环

javascript

// WRONG - for...of
for (var item of items) {
  gs.info(item);
}

// CORRECT - Traditional for loop
for (var i = 0; i < items.length; i++) {
  gs.info(items[i]);
}

javascript

// 错误 - for...of循环
for (var item of items) {
  gs.info(item);
}

// 正确 - 传统for循环
for (var i = 0; i < items.length; i++) {
  gs.info(items[i]);
}

Default Parameters

默认参数

javascript

// WRONG - Default parameters
function process(incident, priority = 3) {
  // ...
}

// CORRECT - Manual defaults
function process(incident, priority) {
  if (typeof priority === 'undefined') {
    priority = 3;
  }
  // ...
}

javascript

// 错误 - 默认参数
function process(incident, priority = 3) {
  // ...
}

// 正确 - 手动设置默认值
function process(incident, priority) {
  if (typeof priority === 'undefined') {
    priority = 3;
  }
  // ...
}

Automatic Validation

自动验证

Before deploying any server-side script:

Check for
```
const
```
/
```
let
```
declarations - convert to
```
var
```
Check for arrow functions
```
=>
```
- convert to
```
function()
```
Check for template literals
```
`
```
- convert to string concatenation
Check for destructuring
```
{a, b}
```
- convert to explicit property access
Check for
```
for...of
```
loops - convert to index-based loops

在部署任何服务器端脚本之前：

检查
```
const
```
/
```
let
```
声明 - 转换为
```
var
```
检查箭头函数
```
=>
```
- 转换为
```
function()
```
检查模板字符串
```
`
```
- 转换为字符串拼接
检查解构
```
{a, b}
```
- 转换为显式属性访问
检查
```
for...of
```
循环 - 转换为基于索引的循环

Exception: Client Scripts

例外情况：客户端脚本

Client-side scripts (Client Scripts, UI Policies) run in the browser and MAY support ES6+ depending on user's browser. However, for maximum compatibility, ES5 is still recommended.

客户端脚本（Client Scripts、UI Policies）在浏览器中运行，根据用户浏览器的不同，可能支持ES6+。不过，为了最大兼容性，仍然推荐使用ES5。