diff --git a/data-extraction/src/js/api/DataExtractorApi.ts b/data-extraction/src/js/api/DataExtractorApi.ts
index 970fa38..af4a176 100644
--- a/data-extraction/src/js/api/DataExtractorApi.ts
+++ b/data-extraction/src/js/api/DataExtractorApi.ts
@@ -17,10 +17,12 @@ export interface DataExtractorApi {
 	registerExtractors(extractors: DataExtractor<ExtractedData>[]): void;
 
 	/**
-	 * Extracts data from `value`.
+	 * Extracts data from the result of `valueFn`.
+	 * @valueFn a function returning the value to extract the data from.
+	 * Is a function so that it's evaluation can depend on `evalFn`.
 	 */
 	getData(
-		value: unknown,
+		valueFn: () => unknown,
 		evalFn: <T>(expression: string) => T,
 		preferredDataExtractorId: string | undefined
 	): JSONString<DataResult>;
diff --git a/data-extraction/src/js/api/DataExtractorApiImpl.ts b/data-extraction/src/js/api/DataExtractorApiImpl.ts
index 1b0e8bb..441dc86 100644
--- a/data-extraction/src/js/api/DataExtractorApiImpl.ts
+++ b/data-extraction/src/js/api/DataExtractorApiImpl.ts
@@ -10,6 +10,8 @@ import { ExtractedData, DataExtractorInfo } from "../../DataExtractionResult";
 import { registerDefaultDataExtractors } from "./default-extractors";
 
 export class DataExtractorApiImpl implements DataExtractorApi {
+	public static lastEvalFn: (<T>(expression: string) => T) | undefined;
+
 	private readonly extractors = new Map<
 		string,
 		DataExtractor<ExtractedData>
@@ -34,7 +36,7 @@ export class DataExtractorApiImpl implements DataExtractorApi {
 	}
 
 	public getData(
-		value: unknown,
+		valueFn: () => unknown,
 		evalFn: <T>(expression: string) => T,
 		preferredDataExtractorId: string | undefined
 	): JSONString<DataResult> {
@@ -45,6 +47,10 @@ export class DataExtractorApiImpl implements DataExtractorApi {
 			},
 		};
 
+		DataExtractorApiImpl.lastEvalFn = evalFn;
+		const value = valueFn();
+		DataExtractorApiImpl.lastEvalFn = undefined;
+
 		for (const e of this.extractors.values()) {
 			e.getExtractions(value, extractionCollector, { evalFn });
 		}
@@ -85,6 +91,7 @@ export class DataExtractorApiImpl implements DataExtractorApi {
 	}
 
 	public registerDefaultExtractors(preferExisting: boolean = false): void {
+		// TODO consider preferExisting
 		registerDefaultDataExtractors(this);
 	}
 }
diff --git a/data-extraction/src/js/helpers/index.ts b/data-extraction/src/js/helpers/index.ts
index b106c10..4f6547f 100644
--- a/data-extraction/src/js/helpers/index.ts
+++ b/data-extraction/src/js/helpers/index.ts
@@ -1,2 +1,3 @@
 export * from "./createGraph";
 export * from "./createGraphFromPointers";
+export * from "./tryEval";
diff --git a/data-extraction/src/js/helpers/tryEval.ts b/data-extraction/src/js/helpers/tryEval.ts
new file mode 100644
index 0000000..bab659c
--- /dev/null
+++ b/data-extraction/src/js/helpers/tryEval.ts
@@ -0,0 +1,48 @@
+import { DataExtractorApiImpl } from "../api/DataExtractorApiImpl";
+
+/**
+ * Takes an object and eval's its values.
+ * Each successfully evaluated value is added to the result object,
+ * its original key is used as key in the result object.
+ *
+ * # Example
+ * ```
+ * const x = 1;
+ * tryEval({ val1: "x", val2: "x y" })
+ * // -> { val1: 1 }
+ * ```
+ */
+export function tryEval(obj: Record<string, string>): Record<string, unknown>;
+/**
+ * Takes an array of strings and eval's its items.
+ * Each successfully evaluated value is added to the result object,
+ * its original value is used as key.
+ *
+ * # Example
+ * ```
+ * const x = 1;
+ * tryEval(["x", "y", "a a", "x + 2"])
+ * // -> { x: 1, "x + 2": 3 }
+ * ```
+ */
+export function tryEval(arr: string[]): Record<string, unknown>;
+export function tryEval(
+	obj: Record<string, string> | string[] | string
+): Record<string, unknown> | unknown {
+	const result: Record<string, unknown> = {};
+	const evalFn = DataExtractorApiImpl.lastEvalFn!;
+	if (Array.isArray(obj)) {
+		for (const val of obj) {
+			try {
+				result[val] = evalFn(val);
+			} catch (e) {}
+		}
+	} else {
+		for (const [key, val] of Object.entries(obj)) {
+			try {
+				result[key] = evalFn(val);
+			} catch (e) {}
+		}
+	}
+	return result;
+}
diff --git a/extension/src/DataSource/JsDebuggerSource.ts b/extension/src/DataSource/JsDebuggerSource.ts
index 2dd5805..c7b6e8f 100644
--- a/extension/src/DataSource/JsDebuggerSource.ts
+++ b/extension/src/DataSource/JsDebuggerSource.ts
@@ -103,7 +103,7 @@ export class JsDebuggerSourceImplementation implements JsDataSource {
 				: "undefined";
 
 			const body = `${getExpressionForDataExtractorApi()}.getData(
-				${w.expression},
+				e => (${w.expression}),
 				expr => eval(expr),
 				${preferredExtractor}
 			)`;