Bootstrap pop-up box centered

1.html page (if the effect does not come out, note modify single quotation marks)

<! DOCTYPE html>
2. Modify Bootstrap.js Source code
Open bootstrap.js ctrl+f find modal corresponding code
Modal.prototype.adjustDialog = function () {    var modalisoverflowing = this. $element [0].scrollheight > Document.documentElement.clientHeight this    . $element. css ({      paddingleft:  !this.bodyisoverflowing && modalisoverflowing? This.scrollbarwidth: "      paddingRight:this.bodyIsOverflowing &&!modalisoverflowing?" This.scrollbarwidth: "    })    //Add the following three lines of code, note to modify single quotation marks!    var $modal _dialog = $ (this. $element [0]). Find ('. Modal-dialog ');    var m_top = ($ (document). Height ()-$modal _dialog.height ())/2;    $modal _dialog.css ({' margin ': M_top + ' px Auto '});  
This is the way to achieve modal vertical center!
Bootstrap pop-up box centered