Js verifies whether the string is a numeric Function

Js verifies whether the string is a numeric function many times we need to verify whether the user input information is a pure number. Now we define the letters as a 0-9 number, in this way, the user input data is compared. If yes, OK.

Whether the character string is a numeric Function
A lot of time, we need to verify whether the user input information is a pure number. Now we define the number 0-9 for letters, so that we can compare the user input data.
*/

Function checkifnumber (str)
{
Var letters = "1234567890 ";
Var I;
Var c;
For (I = 0; I <str. length; I ++)
{
C = str. charat (I );
If (letters. indexof (c) <0)
Return false;
}
Return true;
}
Var tel = 123456;
If (checkifnumber (tel ))
{
Alert ('digit verification pass ');
}
Else
{
Alert ('www. bKjia. c0m. You have entered a non-digit ');
}