javascript-在数组中查找字符串

Question

a little twist on the usual "finding string in an array" question:

I currently know how to find a string in an array, using a for loop and if statement. But what I want to do is return an option if no matching string can be found once iterating through the entire array. The obvious problem is that if I include an else option in my current if-statement, each iteration that there is no match moves to the else.

So basically, I want to scan through the entire array.. IF there's a match I want to print "abc" and if there is no match at all I want to print "xyz". How do I do this? Thanks (super novice here :)).

var guestList = [
"MANDY",
"JEMMA",
"DAVE",
"BOB",
"SARAH",
"MIKE",
"SUZY"
];

var guestName = prompt("Hello, welcome to The Club. What is your name?").toUpperCase();

for (var i=0; i<guestList.length; i++){
    if (guestName === guestList[i]){
        alert("Hi " + guestName + " You are on the list! Enjoy The Club");
    }
}

Answer 1

No for loops required

 if(guestList.indexOf(guestName) === -1) return "xyz" else return "abc" 

Answer 2

If you still want to print the guest name, you can give a default guest name, and than it might be changed or not during the for loop:

    var guestName = prompt("Hello, welcome to The Club. What is your name?").toUpperCase();
    var member = "GUEST";
    for (var i=0; i < guestList.length; i++) {
        if (guestName === guestList[i]){
            member = guestName;
            break;
        }
    }
    alert("Hi " + member);

Or with jQuery and without a for loop:

var member = "GUEST";
if ($.inArray(guestName, guestList) > -1) {
    member = guestName;
}
alert("Hi " + member);

See the documentation of jquery inArray:

http://api.jquery.com/jquery.inarray/

Answer 3

Try this code:

 var guestList = [ "MANDY", "JEMMA", "DAVE", "BOB", "SARAH", "MIKE", "SUZY" ]; var guestName = prompt("Hello, welcome to The Club. What is your name?").toUpperCase(); var greet = "xyz";//put the default text here for (var i = 0; i < guestList.length; i++) { if (guestName === guestList[i]) { greet = "Hi " + guestName + " You are on the list! Enjoy The Club"; break;//match found, stop loop } } alert(greet);//greetings here