Link method which prevent same locations in the history

CHANGES.md

@@ -1,3 +1,5 @@
+- Add `history.link` which navigates and prevents same paths in the history stack (thanks @dabit1)
+
 ## [v4.6.3]
 > Jun 20, 2017
 

README.md

@@ -138,8 +138,10 @@ The `action` is one of `PUSH`, `REPLACE`, or `POP` depending on how the user got
 * `history.goBack()`
 * `history.goForward()`
 * `history.canGo(n)` (only in `createMemoryHistory`)
+* `history.link(path, [state])`
 
 When using `push` or `replace` you can either specify both the URL path and state as separate arguments or include everything in a single location-like object as the first argument.
+When requiring an action to behave like a link (not pushing duplicate paths to the stack) you can use the `link` method.
 
 1. A URL path _or_
 2. A location-like object with `{ pathname, search, hash, state }`

modules/LocationUtils.js

@@ -74,3 +74,9 @@ export const locationsAreEqual = (a, b) =>
   a.hash === b.hash &&
   a.key === b.key &&
   valueEqual(a.state, b.state);
+
+export const shouldReplace = (location, newPath, newState) => {
+  const currentPath = location.pathname + location.search + location.hash;
+
+  return currentPath === newPath && (!location.state || valueEqual(location.state, newState));
+}

modules/__tests__/LocationUtils-test.js

@@ -1,5 +1,5 @@
 import expect from "expect";
-import { createLocation } from "../LocationUtils";
+import { createLocation, shouldReplace } from "../LocationUtils";
 
 describe("createLocation", () => {
   describe("with a full path", () => {
@@ -160,3 +160,71 @@ describe("createLocation", () => {
     });
   });
 });
+
+describe("shouldReplace", () => {
+  it("should return true if current path is the same as new path", () => {
+    const currentLocation = {
+      pathname: "the/path",
+      search: "?the=query",
+      hash: "#the-hash"
+    };
+    expect(shouldReplace(currentLocation, 'the/path?the=query#the-hash')).toBeTruthy();
+  });
+
+  it("should return false if current path is other than new path", () => {
+    const currentLocation = {
+      pathname: "the/path",
+      search: "?the=query",
+      hash: "#the-hash"
+    };
+    expect(shouldReplace(currentLocation, 'the/path?the=query')).toBeFalsy();
+  });
+
+  it("should return true if current path is the same as new path and current state is the same as new state", () => {
+    const currentLocation = {
+      pathname: "the/path",
+      search: "?the=query",
+      hash: "#the-hash",
+      state: {
+        foo: 'bar',
+        obj: {
+          foo2: 'var2'
+        }
+      }
+    };
+    expect(shouldReplace(
+      currentLocation, 
+      'the/path?the=query#the-hash',
+      {
+        foo: 'bar',
+        obj: {
+          foo2: 'var2'
+        }
+      }
+    )).toBeTruthy();
+  });
+
+  it("should return false if current path is the same as new path and current state is other than new state", () => {
+    const currentLocation = {
+      pathname: "the/path",
+      search: "?the=query",
+      hash: "#the-hash",
+      state: {
+        foo: 'bar',
+        obj: {
+          foo2: 'var2'
+        }
+      }
+    };
+    expect(shouldReplace(
+      currentLocation, 
+      'the/path?the=query#the-hash',
+      {
+        foo: 'bar',
+        obj: {
+          foo2: 'var3'
+        }
+      }
+    )).toBeFalsy();
+  });
+});

modules/createBrowserHistory.js

@@ -1,6 +1,6 @@
 import warning from "warning";
 import invariant from "invariant";
-import { createLocation } from "./LocationUtils";
+import { createLocation, shouldReplace } from "./LocationUtils";
 import {
   addLeadingSlash,
   stripTrailingSlash,
@@ -308,12 +308,16 @@ const createBrowserHistory = (props = {}) => {
     };
   };
 
+  const link = (path, state) => 
+    shouldReplace(history.location, path, state) ? replace(path, state) : push(path, state);
+
   const history = {
     length: globalHistory.length,
     action: "POP",
     location: initialLocation,
     createHref,
     push,
+    link,
     replace,
     go,
     goBack,

modules/createHashHistory.js

@@ -1,6 +1,6 @@
 import warning from "warning";
 import invariant from "invariant";
-import { createLocation, locationsAreEqual } from "./LocationUtils";
+import { createLocation, locationsAreEqual, shouldReplace } from "./LocationUtils";
 import {
   addLeadingSlash,
   stripLeadingSlash,
@@ -327,12 +327,16 @@ const createHashHistory = (props = {}) => {
     };
   };
 
+  const link = path =>
+    shouldReplace(history.location, path) ? replace(path) : push(path);
+
   const history = {
     length: globalHistory.length,
     action: "POP",
     location: initialLocation,
     createHref,
     push,
+    link,
     replace,
     go,
     goBack,

modules/createMemoryHistory.js

@@ -1,6 +1,6 @@
 import warning from "warning";
 import { createPath } from "./PathUtils";
-import { createLocation } from "./LocationUtils";
+import { createLocation, shouldReplace } from "./LocationUtils";
 import createTransitionManager from "./createTransitionManager";
 
 const clamp = (n, lowerBound, upperBound) =>
@@ -156,6 +156,9 @@ const createMemoryHistory = (props = {}) => {
 
   const listen = listener => transitionManager.appendListener(listener);
 
+  const link = (path, state) => 
+    shouldReplace(window.location, path, state) ? replace(path, state) : push(path, state);
+
   const history = {
     length: entries.length,
     action: "POP",
@@ -164,6 +167,7 @@ const createMemoryHistory = (props = {}) => {
     entries,
     createHref,
     push,
+    link,
     replace,
     go,
     goBack,