regex and negative numbers

[simon551]

I found this code somewhere that helps me handle formatted numbers on an input. I would like to modify it so it will accept negative numbers (and not convert them to positive)

function convertToDouble(v){
	var str = Number(v.replace(/[^0-9\.]+/g,""));
	num= (parseFloat(str));
	return num;
}

 

[simon551]

I think I figured it out. This worked:
var str = Number(v.replace(/[^-0-9\.]+/g,""));

 

[Bong]

/-*[^0-9\.]+/

_________________
Bob Rashkin

 

[Bong]

You're right. Mine won't work.

_________________
Bob Rashkin

 

[tsuji]

From the name of the function, the approach seems frightenly "wrong"! unless the input v is of a very special pattern only.

This is a suggestion of how these things can be made working more generally. And it becomes more involved.
[tt]
//this function accepts exotic +-+----123.456 etc
//it excludes only integral part be absent like .123.
function extract_num(v) {
var rx=/(-|\+)*\d+\.?\d*/g;
var a=v.match(rx);
return a; //return null of Array type
}

var s="abc12.4pqr--123.56xyz++-14";
var w=extract_num(s);
if (w instanceof Array) {
for (var i=0; i<w.length; i++) {
alert(eval(w.replace(/\+|-/g,RegExp.$1+"1*")));
}
} else {
alert ('no valid number is extracted.');
}
[/tt]
The odd look and the use of eval() is to make exotic case like -- or +- etc work out as valid numbers; and that such as --123.00 will provoke NaN for parseFloat(). Seemingly not very attractive, but functionally it is forced by the necessity.

 

[tsuji]

further notes
The function also ill behaves when there is a sequence of number like 123.456.789. It will take up 123.456 and leave out 789. But in retrospect, how to interprete 123.456.789?!