在JavaScript中将字符串拆分为2个变量

Question

I am wanting to convert a string into 2 variables..

I have created a variable and I am using substring to split it, however I can't seem to get it working.

If I create a alert message it display's the orignal variable that I want split up (so I know there is something there)

My code looks like this:

// variable 'ca' is set from a XML Element Response
alert(ca); // displays a string (eg. 123456789) - which does display fine
alert(ca.substring(0,1));  // should alert 1 but it stops and nothing is displayed

but I add ca = "123456789"; as below, it works..

ca = "123456789";
alert(ca); // displays a string (eg. 123456789) - which does display fine
alert(ca.substring(0,1));  // should alert 1 but it stops and nothing is displayed

however the variable ca has something set and is display right before the substring is used..

anyone know what I might be doing wrong?

Answer 1

Your variable doesn't contain a string, it contains something else, probably a number.

Convert the value to a string, to be able to use string methods on it:

ca = ca.toString();

Answer 2

My guess is that ca doesn't contain a string but a number. Does it work when you cast the variable to a string?

alert(String(ca).substring(0,1));

(Note that you can check what a variable contains with the typeof operator:

console.log(typeof ca);
// number
console.log(typeof String(ca));
// string

UPDATE: both ca.toString() and String(ca) should work, but I personally prefer String(ca) since that will also work if ca is null or undefined .