files/en-us/mozilla/firefox/releases/74/index.md
This article provides information about the changes in Firefox 74 that will affect developers. Firefox 74 was released on March 10, 2020.
$x() web console helper's third argument (result type) now accepts simple string values as well as XPathResult constants (bug 1602591).No changes.
text-underline-position is now enabled by default (bug 1606997).text-underline-offset and text-decoration-thickness properties now accept percentage values (bug 1607534).auto value of the {{cssxref("outline-style")}} property has been enabled by default (Firefox bug 1031664).-moz- prefixed-Multiple-column layout properties have been removed (Firefox bug 1308636).No changes.
javascript:) is evaluated and the result is a string, this string is parsed to create an HTML document, which is then presented. Previously, this document's URL (as reported by the document.location property, for example) was the originating javascript: URL; it is now correctly the URL of the document the javascript: URL was evaluated in (Firefox bug 836567).Object.toSource() method and the global function uneval() are no longer available for use by web content or extensions (bug 1565170).onlanguagechange, which is triggered when the user changes their preferred language (Firefox bug 1154779). This was previously listed in our compatibility database as supported from Firefox 3.5, but this was in error.actualBoundingBoxLeft, actualBoundingBoxRight, actualBoundingBoxAscent, and actualBoundingBoxDescent. Text metrics can be retrieved using the {{domxref("CanvasRenderingContext2D.measureText()")}} method (Firefox bug 1102584).IDBDatabase.mozCreateFileHandle() method has been removed, in favor of the (also non-standard) IDBDatabase.createMutableFile() method (Firefox bug 1024312).IDBMutableFile.getFile() method has been removed (Firefox bug 1607791).mozGetAsFile() has been removed, after being deprecated several years ago (Firefox bug 1588980).Cross-Origin-Resource-Policy header is now enabled by default (bug 1602363).allow attribute, and the embedded page requests permission to use that resource, the parent page prompts the user for permission to use the resource and share it with the embedded domain, rather than both the outer and inner pages prompting the user for permission. If the outer page doesn't have the permission requested by the allow attribute, the <iframe> is immediately denied access without prompting the user Firefox bug 1483631.No changes.
WebDriver:Print to print the current page as a PDF document (Firefox bug 1604506).Webdriver:TakeScreenshot now always captures the top-level browsing context and not the currently-selected browsing context, if no element to capture has been specified (Firefox bug 1398087, Firefox bug 1606794).Webdriver:TakeScreenshot's full argument causes the complete page to be captured (Firefox bug 1571424).shortcut Firefox bug 1475043.urlClassifications are now returned as part of the details in each event of {{WebExtAPIRef("webRequest")}}, providing information on whether a request is classified as fingerprinting or tracking Firefox bug 1589494.No changes.