added: elementOffsetLeft method

Author: GianlucaGuarini

README.md

@@ -50,7 +50,7 @@ Returns **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refer
 
 ### scrollLeft
 
-Return amount of px scrolled from the top of the document
+Return amount of px scrolled from the left of the document
 
 Returns **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** scroll left value in px
 
@@ -63,3 +63,13 @@ Get the offset top of any DOM element
 -   `el` **[HTMLElement](https://developer.mozilla.org/en-US/docs/Web/HTML/Element)** the element we need to check
 
 Returns **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** the element y position in px
+
+### elementOffsetLeft
+
+Get the offset left of any DOM element
+
+**Parameters**
+
+-   `el` **[HTMLElement](https://developer.mozilla.org/en-US/docs/Web/HTML/Element)** the element we need to check
+
+Returns **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** the element x position in px

index.next.js

@@ -85,7 +85,7 @@ export function scrollTop() {
 }
 
 /**
- * Return amount of px scrolled from the top of the document
+ * Return amount of px scrolled from the left of the document
  * @returns { Number } scroll left value in px
  */
 export function scrollLeft() {
@@ -104,4 +104,13 @@ export function scrollLeft() {
  */
 export function elementOffsetTop(el) {
   return max(scrollTop() + el.getBoundingClientRect().top)
+}
+
+/**
+ * Get the offset left of any DOM element
+ * @param { HTMLElement } el - the element we need to check
+ * @returns { Number } the element x position in px
+ */
+export function elementOffsetLeft(el) {
+  return max(scrollLeft() + el.getBoundingClientRect().left)
 }

test.js

@@ -36,4 +36,10 @@ describe('Bianco viewport', function() {
     assert.equal(typeof viewport.elementOffsetTop(div), 'number')
     assert.ok(notNaN(viewport.elementOffsetTop(div)))
   })
+
+  it('elementOffsetLeft is a number', function() {
+    const div = document.createElement('div')
+    assert.equal(typeof viewport.elementOffsetLeft(div), 'number')
+    assert.ok(notNaN(viewport.elementOffsetLeft(div)))
+  })
 })