Merge pull request #1667 from patrickkettner/prefixed-css-property

add prefixedCSSValue, to test for prefixed css values

src/prefixedCSSValue.js

@@ -0,0 +1,51 @@
+define(['ModernizrProto', 'domPrefixes', 'createElement'], function(ModernizrProto, domPrefixes, createElement) {
+  /**
+   * prefixedCSSValue is a way test for prefixed css properties (e.g. display: -webkit-flex)
+   *
+   * @memberof Modernizr
+   * @name Modernizr.prefixedCSSValue
+   * @optionName Modernizr.prefixedCSSValue()
+   * @optionProp prefixedCSSValue
+   * @access public
+   * @function prefixedCSSValue
+   * @param {string} prop - String name of the property to test for
+   * @param {string} value - String value of the non prefixed version of the value you want to test for
+   * @returns {string|false} The string representing the (possibly prefixed)
+   * valid version of the property, or `false` when it is unsupported.
+   * @example
+   *
+   * `Modernizr.prefixedCSSValue` is a way test for prefixed css properties (e.g. display: -webkit-flex)
+   *
+   * ```js
+   * Modernizr.prefixedCSSValue('background', 'linear-gradient(left, red, red)')
+   * ```
+   *
+   */
+
+  var prefixedCSSValue = function(prop, value) {
+    var result = false;
+    var elem = createElement('div');
+    var style = elem.style;
+
+    if (prop in style) {
+      var i = domPrefixes.length;
+
+      style[prop] = value;
+      result = style[prop];
+
+      while (i-- && !result) {
+        style[prop] = '-' + domPrefixes[i] + '-' + value;
+        result = style[prop];
+      }
+    }
+
+    if (result === '') {
+      result = false;
+    }
+
+    return result;
+  };
+
+  ModernizrProto.prefixedCSSValue = prefixedCSSValue;
+  return prefixedCSSValue;
+});

test/browser/src/prefixedCSSValue.js

@@ -0,0 +1,35 @@
+describe('prefixedCSSValue', function() {
+  var prefixedCSSValue;
+  var cleanup;
+
+  before(function(done) {
+
+    var req = requirejs.config({
+      context: Math.random().toString().slice(2),
+      baseUrl: '../src',
+      paths: {cleanup: '../test/cleanup'}
+    });
+
+    req(['cleanup', 'prefixedCSSValue'], function(_cleanup, _prefixedCSSValue) {
+      prefixedCSSValue = _prefixedCSSValue;
+      cleanup = _cleanup;
+      done();
+    });
+  });
+
+  it('returns the value when it is valid', function() {
+    expect(prefixedCSSValue('display', 'block')).to.equal('block');
+  });
+
+  it('returns false when the prop is not supported', function() {
+    expect(prefixedCSSValue('fart', 'block')).to.equal(false);
+  });
+
+  it('returns false when value is not supported', function() {
+    expect(prefixedCSSValue('display', 'fart')).to.equal(false);
+  });
+
+  after(function() {
+    cleanup();
+  });
+});