diff --git a/types/quill/index.d.ts b/types/quill/index.d.ts
index cf7440f428..f8ee7c5d1f 100644
--- a/types/quill/index.d.ts
+++ b/types/quill/index.d.ts
@@ -7,7 +7,16 @@ declare namespace Quill {
 
     type Key = { key: string, shortKey?: boolean };
     type Sources = "api" | "user" | "silent";
-    type Formats = { [key: string]: any };
+    type StringMap = { [key: string]: any };
+    type OptionalAttributes = { attributes?: StringMap };
+    /**
+     * A stricter type definition would be:
+     *
+     *   type DeltaOperation ({ insert: any } | { delete: number } | { retain: number }) & OptionalAttributes;
+     *
+     *  But this would break a lot of existing code as it would require manual discrimination of the union types.
+     */
+    type DeltaOperation = StringMap & OptionalAttributes;
 
     export interface KeyboardStatic {
         addBinding(key: Key, callback: (range: RangeStatic, context: any) => void): void;
@@ -23,7 +32,7 @@ declare namespace Quill {
 
     export interface QuillOptionsStatic {
         debug?: string,
-        modules?: Formats,
+        modules?: StringMap,
         placeholder?: string,
         readOnly?: boolean,
         theme?: string,
@@ -38,26 +47,26 @@ declare namespace Quill {
     }
 
     export interface DeltaStatic {
-        new (ops: Array<any>) : DeltaStatic;
-        new (ops: any) : DeltaStatic;
-        ops?: Array<any>;
-        retain(length: number, attributes: any) : DeltaStatic;
+        new (ops?: DeltaOperation[] | { ops: DeltaOperation[] }) : DeltaStatic;
+        ops?: DeltaOperation[];
+        retain(length: number, attributes?: StringMap) : DeltaStatic;
         delete(length: number) : DeltaStatic;
-        filter(predicate: any) : DeltaStatic;
-        forEach(predicate: any) : DeltaStatic;
-        insert(text: any, attributes: any): DeltaStatic;
-        map(predicate: any) : DeltaStatic;
-        partition(predicate: any) : DeltaStatic;
-        reduce(predicate: any, initial: number): DeltaStatic;
+        filter(predicate: (op: DeltaOperation) => boolean) : DeltaOperation[];
+        forEach(predicate: (op: DeltaOperation) => void) : void;
+        insert(text: any, attributes?: StringMap): DeltaStatic;
+        map<T>(predicate: (op: DeltaOperation) => T) : T[];
+        partition(predicate: (op: DeltaOperation) => boolean) : [DeltaOperation[], DeltaOperation[]];
+        reduce<T>(predicate: (acc: T, curr: DeltaOperation, idx: number, arr: DeltaOperation[]) => T, initial: T): T;
         chop() : DeltaStatic;
         length(): number;
-        slice(start: number, end: number): DeltaStatic;
-        compose(other: any): DeltaStatic;
+        slice(start?: number, end?: number): DeltaStatic;
+        compose(other: DeltaStatic): DeltaStatic;
         concat(other: DeltaStatic): DeltaStatic;
-        diff(other: DeltaStatic, index: number) : DeltaStatic;
-        eachLine(predicate: any, newline: any) : DeltaStatic;
-        transform(other: any, priority: any) : DeltaStatic;
-        transformPosition(index: number, priority: any) : DeltaStatic;
+        diff(other: DeltaStatic, index?: number) : DeltaStatic;
+        eachLine(predicate: (line: DeltaStatic, attributes: StringMap, idx: number) => any, newline?: string) : DeltaStatic;
+        transform(index: number) : DeltaStatic;
+        transform(other: DeltaStatic, priority: boolean) : DeltaStatic;
+        transformPosition(index: number) : DeltaStatic;
     }
 
     export interface RangeStatic {
@@ -77,7 +86,7 @@ declare namespace Quill {
         insertEmbed(index: number, type: string, value: any, source?: Sources): void;
         insertText(index: number, text: string, source?: Sources): DeltaStatic;
         insertText(index: number, text: string, format: string, value: any, source?: Sources): DeltaStatic;
-        insertText(index: number, text: string, formats: Formats, source?: Sources): DeltaStatic;
+        insertText(index: number, text: string, formats: StringMap, source?: Sources): DeltaStatic;
         /**
         * @deprecated Use clipboard.dangerouslyPasteHTML(index: number, html: string, source: Sources)
         */
@@ -94,12 +103,12 @@ declare namespace Quill {
         format(name: string, value: any, source?: Sources): DeltaStatic;
         formatLine(index: number, length: number, source?: Sources): DeltaStatic;
         formatLine(index: number, length: number, format: string, value: any, source?: Sources): DeltaStatic;
-        formatLine(index: number, length: number, formats: Formats, source?: Sources): DeltaStatic;
+        formatLine(index: number, length: number, formats: StringMap, source?: Sources): DeltaStatic;
         formatText(index: number, length: number, source?: Sources): DeltaStatic;
         formatText(index: number, length: number, format: string, value: any, source?: Sources): DeltaStatic;
-        formatText(index: number, length: number, formats: Formats, source?: Sources): DeltaStatic;
-        getFormat(range?: RangeStatic): Formats;
-        getFormat(index: number, length?: number): Formats;
+        formatText(index: number, length: number, formats: StringMap, source?: Sources): DeltaStatic;
+        getFormat(range?: RangeStatic): StringMap;
+        getFormat(index: number, length?: number): StringMap;
         removeFormat(index: number, length: number, source?: Sources): void;
 
         blur(): void;
@@ -118,7 +127,7 @@ declare namespace Quill {
         debug(level: string): void;
         import(path: string): any;
         register(path: string, def: any, suppressWarning?: boolean): void;
-        register(defs: Formats, suppressWarning?: boolean): void;
+        register(defs: StringMap, suppressWarning?: boolean): void;
         addContainer(className: string, refNode?: any): any;
         addContainer(domNode: any, refNode?: any): any;
         getModule(name: string): any
diff --git a/types/quill/quill-tests.ts b/types/quill/quill-tests.ts
index eba77f8b68..dc7800d444 100644
--- a/types/quill/quill-tests.ts
+++ b/types/quill/quill-tests.ts
@@ -187,3 +187,140 @@ function test_PasteHTML2()
     var quillEditor = new Quill('#editor');
     quillEditor.pasteHTML(5, '<h1>Quill Rocks</h1>');
 }
+
+function test_DeltaChaining() {
+    var delta = new Delta()
+        .insert('Hello', { bold: true })
+        .insert('World')
+        .delete(5)
+        .retain(5)
+        .retain(5, { color: '#0c6' });
+
+}
+
+function test_DeltaFilter() {
+    var delta = new Delta().insert('Hello', { bold: true })
+        .insert({ image: 'https://octodex.github.com/images/labtocat.png' })
+        .insert('World!');
+
+    var text = delta.filter(function(op) {
+        return typeof op.insert === 'string';
+    }).map(function(op) {
+        return op.insert;
+    }).join('');
+}
+
+function test_DeltaForEach() {
+    var delta = new Delta();
+    delta.forEach(function(op) {
+        console.log(op);
+    });
+}
+
+function test_DeltaMap() {
+    var delta = new Delta()
+        .insert('Hello', { bold: true })
+        .insert({ image: 'https://octodex.github.com/images/labtocat.png' })
+        .insert('World!');
+
+    var text = delta.map(function(op) {
+      if (typeof op.insert === 'string') {
+          return op.insert;
+      } else {
+          return '';
+      }
+    }).join('');
+}
+
+function test_DeltaPartition() {
+    var delta = new Delta().insert('Hello', { bold: true })
+        .insert({ image: 'https://octodex.github.com/images/labtocat.png' })
+        .insert('World!');
+
+    var results = delta.partition(function(op) {
+        return typeof op.insert === 'string';
+    });
+    var passed = results[0];  // [{ insert: 'Hello', attributes: { bold: true }}, { insert: 'World'}]
+    var failed = results[1];  // [{ insert: { image: 'https://octodex.github.com/images/labtocat.png' }}]
+}
+
+function test_DeltaReduce() {
+    var delta = new Delta().insert('Hello', { bold: true })
+                           .insert({ image: 'https://octodex.github.com/images/labtocat.png' })
+                           .insert('World!');
+
+    var length = delta.reduce(function(length, op) {
+      return length + (op.insert.length || 1);
+    }, 0);
+}
+
+function test_DeltaSlice() {
+    var delta = new Delta().insert('Hello', { bold: true }).insert(' World');
+
+    // {
+    //   ops: [
+    //     { insert: 'Hello', attributes: { bold: true } },
+    //     { insert: ' World' }
+    //   ]
+    // }
+    var copy = delta.slice();
+    console.log(copy.ops);
+
+    // { ops: [{ insert: 'World' }] }
+    var world = delta.slice(6);
+    console.log(world.ops);
+
+    // { ops: [{ insert: ' ' }] }
+    var space = delta.slice(5, 6);
+    console.log(space.ops);
+}
+
+function test_DeltaCompose() {
+    var a = new Delta().insert('abc');
+    var b = new Delta().retain(1).delete(1);
+
+    var composed = a.compose(b);  // composed == new Delta().insert('ac');
+}
+
+function test_DeltaDiff() {
+    var a = new Delta().insert('Hello');
+    var b = new Delta().insert('Hello!');
+
+    var diff = a.diff(b);  // { ops: [{ retain: 5 }, { insert: '!' }] }
+                           // a.compose(diff) == b
+    var diff2 = a.diff(b, 0);  // { ops: [{ retain: 5 }, { insert: '!' }] }
+                               // a.compose(diff) == b
+}
+
+function test_DeltaEachLine() {
+    var delta = new Delta().insert('Hello\n\n')
+                           .insert('World')
+                           .insert({ image: 'octocat.png' })
+                           .insert('\n', { align: 'right' })
+                           .insert('!');
+
+    delta.eachLine(function(line, attributes, i) {
+        console.log(line, attributes, i);
+        // Can return false to exit loop early
+    });
+    // Should log:
+    // { ops: [{ insert: 'Hello' }] }, {}, 0
+    // { ops: [] }, {}, 1
+    // { ops: [{ insert: 'World' }, { insert: { image: 'octocat.png' } }] }, { align: 'right' }, 2
+    // { ops: [{ insert: '!' }] }, {}, 3
+}
+
+function test_DeltaTransform() {
+    var a = new Delta().insert('a');
+    var b = new Delta().insert('b').retain(5).insert('c');
+
+    a.transform(b, true);  // new Delta().retain(1).insert('b').retain(5).insert('c');
+    a.transform(b, false); // new Delta().insert('b').retain(6).insert('c');
+    a.transform(5);
+}
+
+function test_DeltatransformPosition() {
+    var delta = new Delta().retain(5).insert('a');
+    delta.transformPosition(4); // 4
+    delta.transformPosition(5); // 6
+}