What's the best way to execute a code block based on the input of a user if it matches a value in an array?

I've tried two ways to achieve this, please see below:

var cat = ['travel', 'business', 'environment', 'culture', 'football', 'politics', 'world', 'commentisfree', 'lifestyle', 'fashion', 'technology', 'sport', 'money', 'science'];

var userInput = $("#mySearch").val();

for(var i=0; i < cat.length; i++){
    if (userInput == cat[i]){
        // do something
    }else{
        // do something else
    }
}

This worked, however the else condition was executed until it found the value. I then tried to lose the array with the below:

var userInput = $("#mySearch").val();

if ( userInput == 'travel' || 'business' || 'environment' || 'culture' || 'football' || 'politics' || 'world' || 'commentisfree' || 'lifestyle' || 'fashion' || 'technology' || 'sport' || 'money' || 'science' ){
    // do something
}else{
    // do something else
}

This way also works, however, it fires for values that aren't between the condition brackets (not entirely sure why??). Explanations and solutions are more than welcome! I'm new to JS