If you have updated your SharePoint environment (true for Office 365 as well) with recent patches (Service Pack or Cumulative Update) and are suddenly facing problems with any functionality that has been working fine for so long. Do not worry and check this, might help.
Microsoft has made some updates/changes to the default Out Of The Box required site columns (something like Name field - internal name FileLeafRef).
Now required fields show up as a different name in your HTML DOM. The Title attribute for <input> will be changed and "Required Field" is appended to the old display name.
Old display name for Name field - Name New display name for Name field - Name Required Field
var spDocName = $("input[title='Name']"); This line of code would have worked fine earlier as there is field with title="Name" on your page. But will fail after the patch now since title="Name Required Field".
The best way to troubleshoot this kind of issue is using the Browser F12 Developer Tools.
Using developer tools, check the HTML code for the required column which is used in your code to verify if the title is changed.
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