use previous state as base for new state

Author: Fabian Kretzer

lib/FilterHandler.js

@@ -80,16 +80,18 @@ const  withFilterHandler = ComponentToWrap => {
 
         updateFilterConfig(filterFunction, filterComponent, columnName){
             if (columnName !== undefined){
-                let newState = {};
-                if (filterFunction !== undefined){
-                    newState.filterFunctions = Object.assign({}, this.state.filterFunctions);
-                    newState.filterFunctions[columnName] = filterFunction;
-                }
-                if (filterComponent !== undefined){
-                    newState.filterComponents = Object.assign({}, this.state.filterComponents);
-                    newState.filterComponents[columnName] = filterComponent;
-                }
-                this.setState(newState);
+                this.setState((prevState) => {
+                    let newState = {};
+                    if (filterFunction !== undefined){
+                        newState.filterFunctions = Object.assign({}, prevState.filterFunctions);
+                        newState.filterFunctions[columnName] = filterFunction;
+                    }
+                    if (filterComponent !== undefined){
+                        newState.filterComponents = Object.assign({}, prevState.filterComponents);
+                        newState.filterComponents[columnName] = filterComponent;
+                    }
+                    return newState;
+                });
 
             } else {
                 let newState = {};