.start takes an optional parameter

README.md

@@ -35,7 +35,11 @@ This will add `Timeout` and `Interval` to `Date`.
 
 * `start(): this`
 
-  Starts the timer. If the timer is currently paused, it will resume the timer.
+  Starts the timer. If the timer is currently paused, it will resume the timer. If the timer is already done, it will reset it and start as normal.
+
+* `start(timeMS: number): this`
+
+  Starts the timer with the given time. **Only works, if the timer is not running or paused!**
 
 * `stop(): this`
 
@@ -72,6 +76,10 @@ This will add `Timeout` and `Interval` to `Date`.
 
   Starts the interval. If the interval is currently paused, it will resume the interval.
 
+* `start(timeMS: number): this`
+
+  Starts the interval with the given time. **Only works, when the interval is reset!**
+
 * `stop(): this`
 
   Stops the interval and resets it to 0. Acts like `clearInterval`.

index.d.ts

@@ -1,6 +1,7 @@
 export declare class Timeout {
     public constructor(callback: () => void, timeMS: number, autoStart: boolean);
     public start(): this;
+    public start(timeMS: number): this;
     public stop(): this;
     public pause(): this;
     public readonly state: 0 | 1 | 2 | 3;
@@ -10,6 +11,7 @@ export declare class Timeout {
 export declare class Interval {
     public constructor(callback: () => void, timeMS: number, autoStart: boolean);
     public start(): this;
+    public start(timeMS: number): this;
     public stop(): this;
     public pause(): this;
     public readonly state: 0 | 1 | 2;

index.js

@@ -8,10 +8,9 @@ function Timeout(callback, time, autoStart = false) {
     this.state = 0;
     if (autoStart) this.start();
 };
-Timeout.prototype.start = function start(time) {
-    if (arguments.length > 0) { // warning: undocumented feature, not really working
-        this.currentTime = time;
-    }
+Timeout.prototype.start = function start(timeMS) {
+    if (this.state == 3) this.stop();
+    if (arguments.length > 0 && this.state == 0) this.currentTime = timeMS;
     if (this._timerId == -1) {
         if (this.state == 2) {
             this._startedAt = Date.now();
@@ -59,7 +58,8 @@ function Interval(callback, time, autoStart = false) {
     this._isInTimeout = false;
     if (autoStart) this.start();
 };
-Interval.prototype.start = function start() {
+Interval.prototype.start = function start(timeMS) {
+    if (arguments.length > 0 && this.state == 0) this.currentTime = timeMS;
     if (this._timerId == -1) {
         if (this.state == 2) {
             this._lastTrigger = Date.now();