Script.apex help you run JavaScript code in Apex. Basically, it compiles JavaScript code into semantic nodes, which are then evaluated in native Apex. The JavaScript expression parser in Script.apex is porting from jsep.

• Parse JavaScript code into semantic nodes
• Evaluate nodes in Apex
• Parsed nodes are cached to improve performance

Here is how we evaluate arithmatic expressions.

Object result = ScriptEngine.getInstance().eval('1 + 2 * (3 - 1)');

Or we can evaluate expressions consuming variables like this:

Map<String, Object> context = new Map<String, Object>{
    'a' => 1,
    'b' => 2
};
Object result = ScriptEngine.getInstance().eval('a + b', context);

Or we can parse the nodes first, and the evaluate them:

Jsep.Node node = new Jsep('1 + 2').parse();
Object result = ScriptEngine.getInstance().eval(node);

Supported Unary Operator

Supported Logical Operator

Supported Binary Operator

Supported Structure

For example,

ScriptEngine.getInstance.eval('["a", "b"]'); // Array literal

ScriptEngine.getInstance.eval('{ "name": "test", age: 18 }'); // Object literal

Assignment expressions can be parsed, but cannot be evaluated yet.

Functions(methods) can be parsed now, but invocation is not implemented yet.