Implement a class Link method setUnique.

jhermsmeier · Nov 8, 2022 · 67bc8b5 · 67bc8b5
1 parent 53d4c8a
commit 67bc8b5
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diff --git a/README.md b/README.md
@@ -71,12 +71,40 @@ link.rel( 'alternate' )
 ### Setting references
 
 ```js
-link.set({ rel: 'next', uri: 'http://example.com/next' })
+link.set({ uri: 'https://example.com/next', rel: 'next' })
 > Link {
   refs: [
     { uri: 'example.com', rel: 'example', title: 'Example Website' },
     { uri: 'example-01.com', rel: 'alternate', title: 'Alternate Example Domain' },
-    { rel: 'next', uri: 'http://example.com/next' }
+    { rel: 'next', uri: 'https://example.com/next' }
+  ]
+}
+```
+
+### Setting a unique reference
+
+```js
+link.setUnique({
+  uri: 'https://example.com/image.png',
+  rel: 'preload',
+  as: 'image',
+  type: 'image/png'
+})
+> Link {
+  refs: [
+    { uri: 'https://example.com/image.png', rel: 'preload', as: 'image', type: 'image/png' }
+  ]
+}
+
+link.setUnique({
+  uri: 'https://example.com/image.png',
+  rel: 'preload',
+  as: 'image',
+  type: 'image/png'
+})
+> Link {
+  refs: [
+    { uri: 'https://example.com/image.png', rel: 'preload', as: 'image', type: 'image/png' }
   ]
 }
 ```

diff --git a/lib/link.js b/lib/link.js
@@ -40,6 +40,21 @@ function needsQuotes( value ) {
     !TOKEN_PATTERN.test( value )
 }
 
+/**
+ * Shallow compares two objects to check if their properties match.
+ * @param {object} object1 First object to compare.
+ * @param {object} object2 Second object to compare.
+ * @returns {boolean} Do the objects have matching properties.
+ */
+function shallowCompareObjects( object1, object2 ) {
+  return (
+    Object.keys( object1 ).length === Object.keys( object2 ).length &&
+    Object.keys( object1 ).every(
+      ( key ) => key in object2 && object1[ key ] === object2[ key ]
+    )
+  );
+}
+
 class Link {
 
   /**
@@ -101,11 +116,25 @@ class Link {
 
   }
 
+  /** Sets a reference. */
   set( link ) {
     this.refs.push( link )
     return this
   }
 
+  /**
+   * Sets a reference if a reference with similar properties isn’t already set.
+   */
+  setUnique( link ) {
+
+    if( !this.refs.some(( ref ) => shallowCompareObjects( ref, link )) ) {
+      this.refs.push( link )
+    }
+
+    return this
+
+  }
+
   has( attr, value ) {
 
     attr = attr.toLowerCase()

diff --git a/test/api.js b/test/api.js
@@ -84,6 +84,33 @@ context( 'API', function() {
     })
   })
 
+  test( 'setUnique()', function() {
+    var link = new Link()
+    link.setUnique( { uri: 'https://example.com/a', rel: 'preconnect' } )
+    assert.deepEqual(
+      link.refs,
+      [
+        { uri: 'https://example.com/a', rel: 'preconnect' }
+      ]
+    )
+    link.setUnique( { uri: 'https://example.com/b', rel: 'preconnect' } )
+    assert.deepEqual(
+      link.refs,
+      [
+        { uri: 'https://example.com/a', rel: 'preconnect' },
+        { uri: 'https://example.com/b', rel: 'preconnect' }
+      ]
+    )
+    link.setUnique( { uri: 'https://example.com/a', rel: 'preconnect' } )
+    assert.deepEqual(
+      link.refs,
+      [
+        { uri: 'https://example.com/a', rel: 'preconnect' },
+        { uri: 'https://example.com/b', rel: 'preconnect' }
+      ]
+    )
+  })
+
   test( 'parse() multiple', function() {
 
     var links = new Link()