Slider: Fix max calculation, when step is float

Fixes #10721
Closes gh-1398

1 files changed, 20 insertions, 2 deletions

diff --git a/ui/slider.js b/ui/slider.js
index 9cb088c88..33eb55b3e 100644
--- a/ui/slider.js
+++ b/ui/slider.js
@@ -552,8 +552,26 @@ return $.widget( "ui.slider", $.ui.mouse, {
 	},
 
 	_calculateNewMax: function() {
-		var remainder = ( this.options.max - this._valueMin() ) % this.options.step;
-		this.max = this.options.max - remainder;
+		var max = this.options.max,
+			min = this._valueMin(),
+			step = this.options.step,
+			aboveMin = Math.floor( ( max - min ) / step ) * step;
+		max = aboveMin + min;
+		this.max = parseFloat( max.toFixed( this._precision() ) );
+	},
+
+	_precision: function() {
+		var precision = this._precisionOf( this.options.step );
+		if ( this.options.min !== null ) {
+			precision = Math.max( precision, this._precisionOf( this.options.min ) );
+		}
+		return precision;
+	},
+
+	_precisionOf: function( num ) {
+		var str = num.toString(),
+			decimal = str.indexOf( "." );
+		return decimal === -1 ? 0 : str.length - decimal - 1;
 	},
 
 	_valueMin: function() {