feat(sparkline): option support for range coercion

The default behavior is still to adjust thee range to be zero based. This allows for better relative display of the numbers.
If you need absolute numbers dislayed you can use the option `coerceData:false`

src/helpers.js

@@ -117,25 +117,40 @@ function getEpochMillis() {
  * 
  * unlabled is just that ▁▂▄▆█
  * 
+ * Options supported are
+ * 
+ * {
+ * coerceData: true, // coerces the minimum value to zero 
+ * }
+ * 
  * @param {array} data Array of values to plot in the sparkline
  * @param {string} label Text to display before sparkline, if empty or null, will not display any labels
  * @param {object} options Optional options for display, e.g display min,max,last, range coercion
+ * 
  * @returns 
  */
 // eslint-disable-next-line no-unused-vars
 function sparkline(data,label,options) {
-  // TODO add handling if data is object
 
+  options = {
+    coerceData: true,
+    ...options
+  }
+
+  // TODO add handling if data is object
   // Assuming data is array
   const minValue = Math.min(...data)
   const maxValue = Math.max(...data)
   const lastValue = data.slice(-1)[0]
 
-  // coerces the minimum value to zero because the mimimum option is only used for range validation, 
-  // not display https://github.com/sindresorhus/sparkly/blob/9e33eaff891c41e8fb8c8883f62e9821729a9882/index.js#L15
-  // sparkly(open,{minimum:27,maximum:50})
+  // This is the default behavior
+  if ( options.coerceData ) {
+    // coerces the minimum value to zero because the mimimum option is only used for range validation, 
+    // not display https://github.com/sindresorhus/sparkly/blob/9e33eaff891c41e8fb8c8883f62e9821729a9882/index.js#L15
+    // sparkly(open,{minimum:27,maximum:50})
+    data = data.map( x=> x- minValue)
+  }
 
-  data = data.map( x=> x- minValue)
 
   let sparkline
   if (label) {

src/helpers.test.js

@@ -22,5 +22,13 @@ describe('helpers',()=> {
         expect(helper.sparkline(input,label)).toBe(expectedOutput)
     })
 
+    it('should return a sparkline with no range coercion',()=>{
+        const expectedOutput = '▂▄▅▇█'
+        const input = [1,2,3,4,5]
+        const label = ''
+        const options = { coerceData: false }
+        expect(helper.sparkline(input,label, options)).toBe(expectedOutput)
+    })
+
 })