检查值是否为数字做某事

Question

I'm trying to check if a value passed is either a string or a number with the below script

$scope.checkval=function(res){
    console.log(res.profile_id)
    if(angular.isNumber(res.profile_id)){
        console.log('Number');
     }else {
        console.log('Center Code is not a number');
     }
}

from the above code i'm always getting Center code is not a number , though the value passed is numeric

Answer 1

That API is not for checking to see if a string is a number; it's checking to see whether the value already is a number.

The simplest thing to do is use the + unary operator to coerce the value to be a number, and then use !isNaN() to verify that it was in fact a parseable numeric string.

$scope.checkval = function(n) {
  return !isNaN(+n);
};

That'll return true when the value can be converted to an actual number. Note that the constant NaN is also a number, but you probably don't want to include NaN in your definition of "numeric".

Answer 2

isNumber is a pretty accurate function so I personally would believe that the value you are passing is probably a string. But in order to avoid that potential issue you can do this, it will eliminate the potential for a string thats a number, but not correct a string that is not.

$scope.checkval = function(res){
    //unary operator will convert the string into a number if appropriate
    var numberToCheck = +res;
    if (angular.isNumber(numberToCheck)) {
        console.log('Number');
     } else {
        console.log('Center Code is not a number');
     }
}

Pointy's solution is a much better way to go about it if you don't want to/can't use the angular built in functions

Answer 3

是像“ 5”或“ 5”那样传递变量。

res.profile_id = 5; //would come out as true

res.profile_id = '5'; //would come out as false

Answer 4

It is likely that res.profile_id is actually a string.

if you are expecting it to be an integer (like if it is a primary key coming back from the DB), you can caste it explicitly to an int by using:

res.profile_id = parseInt(res.profile_id, 10);

If this is a user input field or it is likely that there would be text in the response, you can test for it like so:

if (!isNaN(res.profile_id){
    ...
}