带双引号插值的Javascript中的字符串比较

Question

I have a javascript variable var a = "SUCCESS"; and while doing some validation I am getting someother value var b = SUCCESS; Now I want to compare

If (a == b){
alert("Allowed");
}else {
alert("Denied");
}   

Above code is not working due to double qoute problem of var b.

Is there any way to compare ("SUCCESS" == SUCCESS) ? I want to assign double quote for variable b.

If we try this way (a == "b") then value of b will not interpolate. Is there any way to use var b inside double quote?

=========

I am adding some more Information here

First of all Thanks a lot Shinpou !! because you are very close to my problem !! var a and var b will not have static values it will be assigned at run time. var a like "Jan" or "Feb" or "Mar" etc.. var b like Jan or Feb or Mar ...If I compare (a == b ) then it will be false.So I want to add double quote to value of var b like perl qq [""]...If qq[""] is not available in Javascript,Can we convert value of var b to a string object ? Finally I want value of var b also like "Jan" or "Feb" etc ..So I can compare "if (a== b) " Thanks again !!!

Answer 1

Short answer is no. It's really questionable what you are trying to do here. a happens to be a variable storing data of type string whose value is "SUCCESS"

b is storing SUCCESS. From your question, it is not clear what SUCCESS means here. If it is another variable defined somewhere else then it is fine. In that case, if var SUCCESS = "SUCCESS", then a == b will give you true.

But if SUCCESS is not defined at all, then your comparison is equivalent to a == undefined

Answer 2

As I understand from your question, you have two variables:

var a = "SUCCESS",
    b = SUCCESS;

If you are declaring the variables as I just did, you are assigning the SUCCESS string to the a variable, while your b variable will equal to the SUCCESS VARIABLE. Basically, if you would want to check for (a == b) and expect a true evaluation, you would have to define the SUCCESS variable and assign it the same value as the a variable:

var SUCCESS = "SUCCESS",
    a = "SUCCESS",
    b = SUCCESS;

a == b // now true

If you do not declare the SUCCESS variable and try to assign it as a value to another variable, you will get a Reference Error when you are comparing a and b, because you didn't declare any SUCCESS variable in your code.

Also, regarding your (a == "b") comparison, when you write it like this (considering the fact that your a variable holds the "SUCCESS" string, this condition would evaluate the following:

(a == "b") // this is basically "SUCCESS" == "b", which obviously will return false, since the strings are different

It's easy to convert an existing variable to a string, but your first need to make sure that you declared that variable and have assigned a value to it. Simply use the toString() function on the variable in order to change its type to string:

var a = 25;

console.log(a); // This will print 25
console.log(typeof a); // This will print Number

a = a.toString(); // This will convert a from 25 to "25"

console.log(a) // Now, this will print "25"
console.log(typeof a); // You will see that a is a String now