parseInt always returns NaN?

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太阳男子
太阳男子 2020-12-06 12:48

long story short, i was trying to validate a phone field. ive added the isNaN and parseInt for checking the \" \" in the field but tha

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  •  误落风尘
    2020-12-06 13:15

    Various ways to coerse JS strings to numbers, and their consequences:


    (source: phrogz.net)

    I personally use *1 as it is short to type, but still stands out (unlike the unary +), and either gives me what the user typed or fails completely. I only use parseInt() when I know that there will be non-numeric content at the end to ignore, or when I need to parse a non-base-10 string.

    Edit: Based on your comment, if using phone.val() fixed it then

    1. You were using jQuery (which you never mentioned, and should have), and
    2. You actually had/have a jQuery object, wrapping one or more DOM elements (probably just one).

    Whenever you do var foo = $('…'); then the foo variable references a jQuery object of one or more elements. You can get the first actual DOM element from this via var fooEl = foo[0]; or var fooEl = foo.get(0);…but even then you still have a DOM element and not a particular property of that.

    For form inputs, you need to get the .value from the DOM element, which is what the jQuery .val() method does.

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