how to check for null and non-number data enterd(like characters or special char)in to text box by using java script?

hi i have a page having text box. in that i should not allow user to go to next page unless he enters some NUMBER. it should numb开发者_如何转开发er but not text and should not be empty , any help pls?

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Try this:

isNaN(yourText.value)

return true if its Not a Number

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The title references checking for null, so you might also want to look at the null object in javascript.