readEx

[ Function ]

Version 1.8

public static readEx(expression: string): any;

Version 1.12

public static readEx<T = any>(expression: string): T;

Reads the value of a symbol addressed via the symbol expression.

From version 1.10, symbol queries are executed directly against the component that makes the data available. Since a synchronous query of symbols from the server is not possible, please use the function readEx2 to query server symbols.

Version 1.12: If the API is used in TypeScript code, the TypeScript compiler can be notified of the symbol value type.

This is a merely an auxiliary programming feature. The browser does not recognize this "type annotation". No check or conversion takes place at runtime.

Parameter

Return value

Available from 1.8

Sample - JavaScript

var symVal = TcHmi.Symbol.readEx('%i%myInternalSym%/i%');

Sample 1 - TypeScript

let symVal = TcHmi.Symbol.readEx('%i%myInternalSym%/i%'); // TS does not know the variable type

Sample 2 - TypeScript

let thisIsABoolean = TcHmi.Symbol.readEx<boolean>('%i%myInternalSym%/i%'); // TS knows this is a boolean