Check for number within a url using javascript?

Question

I've a gallery within a website and each gallery image is represented by a url like so:

http://www.example.com/gallery/my-photos#10

http://www.example.com/gallery/my-photos#11

http://www.example.com/gallery/my-photos#12

. . . . .

I've created a conditional statement to prevent user from invalid url.

var galleryNum = window.location.hash.substring(1);

if( typeof(galleryNum) == "string" || typeof(galleryNum) == "NaN" ){
    console.log('this is not a number');
}else if(typeof(galleryNum) == "number"){
    console.log('this is a number');
}

However this doesn't work, the value I get from window.location.hash.substring(1) will always be a string regardless I enter number or a string.

Yangguang · Accepted Answer · 2015-05-21 04:46:15Z

3

if you want to get number, you should use:

parseInt(galleryNum,10)

if you want to check whether galleryNum is number or not, you can use:

isNaN(parseInt(galleryNum,10))

edited May 21, 2015 at 4:46

answered May 21, 2015 at 4:41

Yangguang

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2 Comments

Rob M. Over a year ago

you should add the radix parameter: parseInt(galleryNum, 10)

John Over a year ago

Yes you definitley should use the radix parameter it does some unwanted things in older versions of ecmascript.

guest271314 · Accepted Answer · 2015-05-21 04:42:56Z

3

Try utilizing .test()

if( /\d/.test(galleryNum) ) {
  // `Number`
} else {
  // not `Number`
}

answered May 21, 2015 at 4:42

guest271314

1

Comments

illuminaut · Accepted Answer · 2015-05-21 06:46:22Z

2

there is no "NaN" type. In fact, despite NaN standing for Not-a-Number, it actually is a number: typeof NaN === 'number'

You can however use isNaN() to test for NaN. To test if the string returned from the URL can be cast to a number, use parseInt:

var galleryNum = parseInt(window.location.hash.substring(1),10);
if (typeof(galleryNum) === 'number' && !isNan(galleryNum)) {
    // got a number here
}

edited May 21, 2015 at 6:46

answered May 21, 2015 at 4:46

illuminaut

3202 silver badges10 bronze badges

3 Comments

John Over a year ago

This is true, but it still doesn't solve his problem.

illuminaut Over a year ago

You are right. I was focusing on an irrelevant part of his question.

John Over a year ago

That's okay it's good for him to know either way. It may be better suited as a comment though.

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