检查变量是否是一个数字-Checkthatvariableisanumber

24  

I'd go with

我一起去

isFinite(String(foo))

See this answer for an explanation why. If you only want to accept integer values, look here.

请看这个答案来解释为什么。如果您只想接受整数值，请查看这里。

37  

The Javascript function isNaN(variable) should do the trick. It returns true if the data is not a number.

Javascript函数isNaN(变量)应该可以做到这一点。如果数据不是数字，则返回true。

11  

function isNumber( input ) {
    return !isNaN( input );
}

isNumber({}) // false 

isNumber('13') // true

isNumber(13) // true

isNumber('test') // false

3  

I'm pretty new to Javascript but it seems like typeof(blah) lets you check if something is a number (it doesn't say true for strings). A know the OP asked for strings + numbers but I thought this might be worth documenting for other people.

我对Javascript很陌生，但是它看起来像是typeof(blah)，让你检查某个东西是否是一个数字(它没有对字符串说true)。A知道OP要求字符串+数字，但我认为这可能值得其他人记录。

eg:

例如:

function isNumeric(something){
    return typeof(something) === 'number';
}

Here are the docs

这是文档

and here's a few console runs of what typeof produces:

这里有一些控制台运行什么类型的产品:

typeof(12);
"number"
typeof(null);
"object"
typeof('12');
"string"
typeof(12.3225);
"number"  

one slight weirdness I am aware of is

我所意识到的一点奇怪之处是

typeof(NaN);
"number"

but it wouldn't be Javascript without something like that right?!

但是没有这样的东西就不是Javascript，对吧?!

1  

function isNumeric( $probe )
{
    return parseFloat( String( $probe ) ) == $probe;
}

1  

You should use:

你应该使用:

var x = 23;
var y = 34hhj;

isNaN(x); 
isNaN(y); 

It will return true if its string and false if its a number.

如果它的字符串是true，则返回false。

1  

See isNan

看到isNan

EDIT: Please look at what Christoph has suggested above. It makes sense to use isFinite as suggested.

编辑:请参阅上面Christoph的建议。使用islimited是有意义的。

1  

You should use:

你应该使用:

if(Number.isInteger(variable))
   alert(variable+variable);
else
   alert("It is not a integer");

you can find the reference in: Number.isInteger()

您可以在:Number.isInteger()中找到引用

0  

You should use

你应该使用

simple way to check whether given value is number by using "if condition"

使用“if条件”检查给定值是否为数字的简单方法

function isInteger(value)      
{       
    num=value.trim();         
    return !(value.match(/\s/g)||num==""||isNaN(num)||(typeof(value)=='number');        
}

it will return true if the value which we are passing is an integer..

如果我们传递的值是一个整数，它将返回true。

solved for     
value=""      //false null     
value="12"    //true only integers       
value="a"     //false     
value=" 12"   //false      
value="12 "   //false         
value=" "     //false space        
value="$12"   //false special characters 
value="as12"    //false

0  

Be aware that empty string '' and ' ' will be considered as number by isNaN and isFinite.

请注意，isNaN和islimited将空字符串“和”视为数字。

0  

You should use: $.isNumeric( i )

您应该使用:$。isNumeric(我)

jQuery.isNumeric API

jQuery。isNumeric API