For a variable x=5, how do I know it is number five or the character '5'?
Btw, in JS, do characters follow the ASCII table? Then can I manipulate a character variable. For example, if variable x is character a, can I do x=x+1 to make it character b?
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Don't ask two different questions in the same question. And doing at least a cursory glance at google might help you answer your own questions.J. Holmes– J. Holmes2012-06-06 02:58:53 +00:00Commented Jun 6, 2012 at 2:58
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Regarding the second part of your question, why don't you just try and see what happens, if you already know what to expect?haylem– haylem2012-06-06 02:59:13 +00:00Commented Jun 6, 2012 at 2:59
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I thought questions like this would get mostly "google it" and massive downvotes, I'm surprised to see a flurry of answers below though...Andreas Wong– Andreas Wong2012-06-06 03:00:22 +00:00Commented Jun 6, 2012 at 3:00
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@SiGanteng: sometimes it takes about the same time to type lmgtfy than to type an actually helpful answer. Plus we do tend to make the same mistake over and over of trying to help people who can't help themselves. We're naturally trustring and naive. :)haylem– haylem2012-06-06 03:01:57 +00:00Commented Jun 6, 2012 at 3:01
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5 Answers
To see if x is the number 5, as opposed to the string "5", you can use the identity operator:
if (x === 5) {
}
Identity will not do any implicit conversions; it will return true only if both operands are equal without any conversions.
For example, if variable x is character a, can I do x=x+1 to make it character b?
No. x = x + 1 will convert 1 to a string, perform string concatenation and return "a1"
2 Comments
OneZero
triple equal signs? is it supposed to be double?
Andreas Wong
triple checks for type and value, it's a stricter checking than using two
=You can use
typeof x;
which returns a string describing the type of the variable, like number, string or object.
To get the character code of a character, use charCodeAt:
var mystring = 'a';
mystring.charCodeAt(0);
And to get a character from an augmented char code, use String.fromCharCode :
var nextLetter = String.fromCharCode( mystring.charCodeAt(0) + 1 ); // returns "b"
This creates a new string from the incremented char code from the first character in mystring.
Comments
Just get the type of the variable:
console.log(typeof '5'); // Returns 'string';
console.log(typeof 5); // Returns 'number';
As for your second question, no, it doesn't work:
console.log('b' + 1); // Returns 'b1'
4 Comments
OneZero
How about "var x=5"? Is is a number or a char?
haylem
@user1229490: I think you're a bit confused.
var x = 5; console.log(typeof x); // outputs 'number'
Blender
You defined it as a number, so therefore it is a number?
Jonathan Lonowski
@user1229490 Javascript doesn't have a
char type. It's either a String or a Number.To check if a variable is a number:
if (typeof x == 'number')
// x is a number
Doing this x = x + 1 when x = b, would result in the string 'a1';
If your var x is not an integer, this is the best way to change it to integer..
To change the x to integer
x = parseInt(x);
You can how add any value to the x, example:
x = x + 2;
Since we have changed the x to integer, we can now identify if this is equal to 5
if(x == 5){
//Your Codes Here
}
