如何在jQuery中强制失去表单中所有字段的焦点

When a input field changes (onchange) I trigger a function to set a variable. The only problem is that the field first has to lose focus before the variable is set and I can check if the field(s) is changed, this is what I want to do when the user clicks on a tab so I can check if the user is forgotten to submit his form in the previous tab. Ho to force lose focus of all possible fields, so first the When a input field changes (onchange) I trigger