diff --git a/src/Components/TriggerEditForm/TriggerEditForm.tsx b/src/Components/TriggerEditForm/TriggerEditForm.tsx
index cab316603..a0dca3f35 100644
--- a/src/Components/TriggerEditForm/TriggerEditForm.tsx
+++ b/src/Components/TriggerEditForm/TriggerEditForm.tsx
@@ -12,7 +12,7 @@ import {
 import { defaultNumberEditFormat, defaultNumberViewFormat } from "../../helpers/Formats";
 import FormattedNumberInput from "../FormattedNumberInput/FormattedNumberInput";
 import ScheduleEdit from "../ScheduleEdit/ScheduleEdit";
-import TriggerModeEditor, { ValueType } from "../TriggerModeEditor/TriggerModeEditor";
+import { ValueType, TriggerModeEditor } from "../TriggerModeEditor/TriggerModeEditor";
 import StatusSelect from "../StatusSelect/StatusSelect";
 import TagDropdownSelect from "../TagDropdownSelect/TagDropdownSelect";
 import { Status, StatusesList } from "../../Domain/Status";
diff --git a/src/Components/TriggerModeEditor/Components/TooltipExpressionHelp/TooltipExpressionHelp.tsx b/src/Components/TriggerModeEditor/Components/TooltipExpressionHelp/TooltipExpressionHelp.tsx
new file mode 100644
index 000000000..9523ac049
--- /dev/null
+++ b/src/Components/TriggerModeEditor/Components/TooltipExpressionHelp/TooltipExpressionHelp.tsx
@@ -0,0 +1,36 @@
+import React from "react";
+import { Link } from "@skbkontur/react-ui/components/Link";
+import CodeRef from "../../../CodeRef/CodeRef";
+import classNames from "classnames/bind";
+
+import styles from "../../TriggerModeEditor.less";
+
+const cn = classNames.bind(styles);
+
+export const TooltipExpressionHelp = (): React.ReactNode => (
+    <div className={cn("expression-help")}>
+        <div className={cn("main-description")}>
+            Expression uses{" "}
+            <Link target="_blank" href="https://github.com/Knetic/govaluate/blob/master/MANUAL.md">
+                govaluate
+            </Link>{" "}
+            with predefined constants:
+        </div>
+        <div>
+            <CodeRef>t1</CodeRef>, <CodeRef>t2</CodeRef>, ... are values from your targets.
+        </div>
+        <div>
+            <CodeRef>OK</CodeRef>, <CodeRef>WARN</CodeRef>, <CodeRef>ERROR</CodeRef>,{" "}
+            <CodeRef>NODATA</CodeRef> are states that must be the result of evaluation.
+        </div>
+        <div>
+            <CodeRef>PREV_STATE</CodeRef> is equal to previously set state, and allows you to
+            prevent frequent state changes.
+        </div>
+
+        <div className={cn("note")}>
+            NOTE: Only T1 target can resolve into multiple metrics in Advanced Mode. T2, T3, ...
+            must resolve to single metrics.
+        </div>
+    </div>
+);
diff --git a/src/Components/TriggerModeEditor/TriggerModeEditor.tsx b/src/Components/TriggerModeEditor/TriggerModeEditor.tsx
index 0433ddc83..a9ea2e057 100644
--- a/src/Components/TriggerModeEditor/TriggerModeEditor.tsx
+++ b/src/Components/TriggerModeEditor/TriggerModeEditor.tsx
@@ -1,13 +1,12 @@
-import * as React from "react";
+import React, { FC, useState } from "react";
 import { ValidationWrapperV1, tooltip, ValidationInfo } from "@skbkontur/react-ui-validations";
 import { Tabs } from "@skbkontur/react-ui/components/Tabs";
 import { Input } from "@skbkontur/react-ui/components/Input";
-import { Link } from "@skbkontur/react-ui/components/Link";
 import { Trigger, TriggerType } from "../../Domain/Trigger";
 import TriggerSimpleModeEditor from "../TriggerSimpleModeEditor/TriggerSimpleModeEditor";
 import { RowStack, Fit, Fill } from "../ItemsStack/ItemsStack";
-import CodeRef from "../CodeRef/CodeRef";
 import HelpTooltip from "../HelpTooltip/HelpTooltip";
+import { TooltipExpressionHelp } from "./Components/TooltipExpressionHelp/TooltipExpressionHelp";
 import classNames from "classnames/bind";
 
 import styles from "./TriggerModeEditor.less";
@@ -21,7 +20,7 @@ export type ValueType = {
     error_value: number | null;
 };
 
-type Props = {
+type IProps = {
     disableSimpleMode?: boolean;
     triggerType: TriggerType;
     value: ValueType;
@@ -30,146 +29,92 @@ type Props = {
     onChange: (update: Partial<Trigger>) => void;
 };
 
-type State = {
-    mode: string;
-    watchFor: WatchForType;
-    risingValues: ValueType;
-    fallingValues: ValueType;
-};
-
-export default class TriggerModeEditor extends React.Component<Props, State> {
-    static getDerivedStateFromProps(props: Props): State {
-        const modeType = TriggerModeEditor.getModeType(props.triggerType);
-        const watchForType = TriggerModeEditor.getWatchForType(props.triggerType);
-
-        return {
-            mode: modeType,
-            watchFor: watchForType,
-            risingValues:
-                watchForType === "rising" ? props.value : { warn_value: null, error_value: null },
-            fallingValues:
-                watchForType === "falling" ? props.value : { warn_value: null, error_value: null },
-        };
-    }
-
-    static getWatchForType(type: string): WatchForType {
+export const TriggerModeEditor: FC<IProps> = ({
+    disableSimpleMode,
+    triggerType,
+    value,
+    expression,
+    validateExpression,
+    onChange,
+}) => {
+    const getWatchForType = (type: string): WatchForType => {
         return type === "falling" ? type : "rising";
-    }
+    };
 
-    static getModeType(type: string): string {
+    const getModeType = (type: string): string => {
         return type === "expression" ? "advanced" : "simple";
-    }
-
-    render(): React.ReactElement {
-        const { mode, watchFor, risingValues, fallingValues } = this.state;
-        const { expression, disableSimpleMode, validateExpression, onChange } = this.props;
+    };
 
-        return (
-            <>
-                <div className={cn("tabs")}>
-                    <Tabs value={mode} onValueChange={this.handleTabChange}>
-                        <Tabs.Tab id="simple" style={{ color: disableSimpleMode ? "#888888" : "" }}>
-                            Simple mode
-                        </Tabs.Tab>
-                        <Tabs.Tab id="advanced">Advanced mode</Tabs.Tab>
-                    </Tabs>
-                </div>
-                {mode === "simple" && (
-                    <TriggerSimpleModeEditor
-                        watchFor={watchFor}
-                        risingValues={risingValues}
-                        fallingValues={fallingValues}
-                        onChange={this.handleInputChange}
-                        onSwitch={this.handleRadioChange}
-                    />
-                )}
-                {mode === "advanced" && (
-                    <div className={cn("advanced")}>
-                        <RowStack verticalAlign="baseline" block>
-                            <Fill>
-                                <ValidationWrapperV1
-                                    validationInfo={validateExpression(
-                                        expression,
-                                        "Expression can't be empty"
-                                    )}
-                                    renderMessage={tooltip("right middle")}
-                                >
-                                    <Input
-                                        width="100%"
-                                        value={expression}
-                                        onValueChange={(value) => onChange({ expression: value })}
-                                        placeholder="t1 >= 10 ? ERROR : (t1 >= 1 ? WARN : OK)"
-                                    />
-                                </ValidationWrapperV1>
-                            </Fill>
-                            <Fit>
-                                &nbsp;
-                                <HelpTooltip>{this.tooltipExpressionHelp()}</HelpTooltip>
-                            </Fit>
-                        </RowStack>
-                    </div>
-                )}
-            </>
-        );
-    }
+    const [mode, setMode] = useState<string>(getModeType(triggerType));
+    const [watchForField, setWatchForField] = useState<WatchForType>(getWatchForType(triggerType));
+    const [values, setValues] = useState<ValueType>(value);
 
-    handleTabChange = (value: string): void => {
-        const { watchFor } = this.state;
-        const { disableSimpleMode, onChange } = this.props;
+    const handleTabChange = (value: string): void => {
         if (!disableSimpleMode) {
-            const triggerType = value === "advanced" ? "expression" : watchFor;
+            const triggerType = value === "advanced" ? "expression" : watchForField;
             onChange({ trigger_type: triggerType });
+            setMode(value);
         }
     };
 
-    handleRadioChange = (type: WatchForType): void => {
-        const { risingValues, fallingValues } = this.state;
-        const { onChange } = this.props;
-        const value = type === "falling" ? { ...fallingValues } : { ...risingValues };
-        this.setState({ watchFor: type });
-        onChange({ trigger_type: type, ...value });
+    const handleRadioChange = (type: WatchForType): void => {
+        setWatchForField(type);
+        onChange({ trigger_type: type, ...values });
     };
 
-    handleInputChange = (value: number | null, valueType: string): void => {
-        const { watchFor, risingValues, fallingValues } = this.state;
-        const { onChange } = this.props;
-        if (watchFor === "rising") {
-            this.setState({ risingValues: { ...risingValues, [valueType]: value } });
-        }
-        if (watchFor === "falling") {
-            this.setState({ fallingValues: { ...fallingValues, [valueType]: value } });
-        }
+    const handleInputChange = (value: number | null, valueType: string): void => {
+        setValues((prev) => ({ ...prev, [valueType]: value }));
         onChange({ [valueType]: value });
     };
 
-    tooltipExpressionHelp = (): React.ReactNode => (
-        <div className={cn("expression-help")}>
-            <div className={cn("main-description")}>
-                Expression uses{" "}
-                <Link
-                    target="_blank"
-                    href="https://github.com/Knetic/govaluate/blob/master/MANUAL.md"
-                >
-                    govaluate
-                </Link>{" "}
-                with predefined constants:
-            </div>
-            <div>
-                <CodeRef>t1</CodeRef>, <CodeRef>t2</CodeRef>, ... are values from your targets.
-            </div>
-            <div>
-                <CodeRef>OK</CodeRef>, <CodeRef>WARN</CodeRef>, <CodeRef>ERROR</CodeRef>,{" "}
-                <CodeRef>NODATA</CodeRef> are states that must be the result of evaluation.
-            </div>
-            <div>
-                <CodeRef>PREV_STATE</CodeRef> is equal to previously set state, and allows you to
-                prevent frequent state changes.
-            </div>
-
-            <div className={cn("note")}>
-                NOTE: Only T1 target can resolve into multiple metrics in Advanced Mode. T2, T3, ...
-                must resolve to single metrics.
+    const configureValues = (watchForType: WatchForType) =>
+        watchForField === `${watchForType}` ? values : { warn_value: null, error_value: null };
+
+    return (
+        <>
+            <div className={cn("tabs")}>
+                <Tabs value={mode} onValueChange={handleTabChange}>
+                    <Tabs.Tab id="simple" style={{ color: disableSimpleMode ? "#888888" : "" }}>
+                        Simple mode
+                    </Tabs.Tab>
+                    <Tabs.Tab id="advanced">Advanced mode</Tabs.Tab>
+                </Tabs>
             </div>
-        </div>
+            {mode === "simple" && (
+                <TriggerSimpleModeEditor
+                    watchFor={watchForField}
+                    risingValues={configureValues("rising")}
+                    fallingValues={configureValues("falling")}
+                    onChange={handleInputChange}
+                    onSwitch={handleRadioChange}
+                />
+            )}
+            {mode === "advanced" && (
+                <div className={cn("advanced")}>
+                    <RowStack verticalAlign="baseline" block>
+                        <Fill>
+                            <ValidationWrapperV1
+                                validationInfo={validateExpression(
+                                    expression,
+                                    "Expression can't be empty"
+                                )}
+                                renderMessage={tooltip("right middle")}
+                            >
+                                <Input
+                                    width="100%"
+                                    value={expression}
+                                    onValueChange={(value) => onChange({ expression: value })}
+                                    placeholder="t1 >= 10 ? ERROR : (t1 >= 1 ? WARN : OK)"
+                                />
+                            </ValidationWrapperV1>
+                        </Fill>
+                        <Fit>
+                            &nbsp;
+                            <HelpTooltip>{TooltipExpressionHelp()}</HelpTooltip>
+                        </Fit>
+                    </RowStack>
+                </div>
+            )}
+        </>
     );
-}
+};
diff --git a/src/Stories/TriggerModeEditor.stories.tsx b/src/Stories/TriggerModeEditor.stories.tsx
index e1f080208..274b455ae 100644
--- a/src/Stories/TriggerModeEditor.stories.tsx
+++ b/src/Stories/TriggerModeEditor.stories.tsx
@@ -2,7 +2,7 @@ import * as React from "react";
 import { storiesOf } from "@storybook/react";
 import { action } from "@storybook/addon-actions";
 import { ValidationContainer } from "@skbkontur/react-ui-validations";
-import TriggerModeEditor from "../Components/TriggerModeEditor/TriggerModeEditor";
+import { TriggerModeEditor } from "../Components/TriggerModeEditor/TriggerModeEditor";
 
 storiesOf("TriggerModeEditor", module)
     .addDecorator((story) => (