How to specify multiple conditions in an if statement in javascript

Just add them within the main bracket of the if statement like:

if ((Type == 2 && PageCount == 0) || (Type == 2 && PageCount == '')) {
    PageCount = document.getElementById('<%=hfPageCount.ClientID %>').value;
}

Logically, this can be rewritten in a better way too! This has exactly the same meaning:

if (Type == 2 && (PageCount == 0 || PageCount == '')) {

Here is an alternative way to do that.

const conditionsArray = [
    condition1,
    condition2,
    condition3,
]

if (conditionsArray.indexOf(false) === -1) {
    "Do something"
}

Or ES7 (or later):

if (!conditionsArray.includes(false)) {
   "Do something"
}

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