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Check If The Card Num Is Int


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function isInt() {var newValue = document.ccForm.number.value;var extraChars=" ";var search;for(i=0; i != newValue.length;i++ {aChar = newValue.substring(i ,i+1);search = extraChars.indexOf(aChar);if(search == -1 && (aChar < "0" || aChar > "9")) {return false;}}return true;the function is working properly but i'm bit confused with the search var it's set up to search for spaces in the number what i want know how the search is bigger than -1 and it should be -1 if there isn't spacesplease help

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I posted some stuff earlier, but I like these better. First we have an isInt() function, and you can pass it anything (number, string, array, undefined variable) and get the correct response: a Boolean true or false. That is, a true integer returns true, and a string containing an integer returns true. An empty string returns false.

function isInt (n) {	if (typeof n == "number") {		return (parseInt(n) == n)	} else if (typeof n == "string") {		if (n.length) {			return !n.match(/\D/);		}	}	return false;}

If anyone has the need, here's a way to do it by re-prototyping both the Number and the String objects.

// Put these statements in your global spaceif (!Number.prototype.isInt) {	Number.prototype.isInt = function () {		return (parseInt(this) == this);	}}if (!String.prototype.isInt) {	String.prototype.isInt = function () {		if (this.length) {			return !this.match(/\D/);		}		return false;	}}

Use them like this:

n = 3;if (isInt(n) ) {	// it's an int}n = 9;if (n.isInt() ) {	// it's an int}s = "7";if (s.isInt() ) {	// it's an int}

FWIW: parseInt() and Number() don't mind if the argument has blank spaces before or after the number characters, so a thing like " 5 " gets parsed as 5. The way I used those functions originally meant that my earlier functions allowed such a string to pass the test. The revised versions (what you see above) do not.

Edited by Deirdre's Dad
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