验证文本输入是否为数字-JavaScript

Question

I am trying to validate user input to make sure that what they type (if anything - field is not required) is a number. Now I don't care what this number is, but it must be an integer. Negative, positive, whatever is validated later on. Here is my test sample so far:

var a=["",0,"0",-2,"-2",2,"2",-2.2,"-2.2",2.2,"2.2",-1,"-1",undefined,null,NaN,Infinity,-Infinity],x;

for(x=0;x<a.length;x++){
    console.log(a[x],(isNaN(+a[x]) || Math.round(+a[x]) != +a[x] || +a[x] === null || +a[x]+1==+a[x])?false:true);
}

If you run that in a console, it shows true for any element in a which would pass the validation, false otherwise. This validation works as expected for me in Chrome ( false is shown for all decimals, and everything from undefined onward.

My question is, will this work in all major browsers (IE 6+ included), and have I completely checked this against every possible input?

As a note:

• + is used in front of the a[x] for type-converting (and also trimming strings - " 2 " gets converted to 2 .

• The last check, +a[x]+1===+a[x] is what checks against (+/-)Infinity .

Thanks :) .

Answer 1

Try this function

function is_int(value){
   if((parseFloat(value) == parseInt(value)) && !isNaN(value)){
      alert("Is an Integer");
     } else {
      alert("Is not an Integer");
     }
   }

is_int(1); //Output - Is an Integer
is_int("a"); //Output - Is not an Integer