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I'm trying to get compound assignment working inside a loop in Javascript but it's throwing NaN at me and I don't know why as I'm still fairly new to Javascript. I am essentially trying to translate this into a jQuery-Validation custom method: https://github.com/pfwd/NHSNumber-Validation/blob/master/PHP/NHSValidation.class.php

Here's what I have so far

        // Taken from https://github.com/pfwd/NHSNumber-Validation
        var multipliers = {1:10, 2:9, 3:8, 4:7, 5:6, 6:5, 7:4, 8:3, 9:2};
        var currentSum, currentNumber, currentMultiplier = 0;

        //Get submitted NHS Number and remove whitespace
        var givenNumber = value.replace(/\s+/g, '');

        // Get length
        var numberLength = givenNumber.length;
        console.debug(givenNumber);
        console.debug(numberLength);

        // Number must be 10 digits in length
        if (numberLength !== 10) {
            return false;
        }

        // Check number
        var checkNumber = value.substring(9);
        console.debug(checkNumber);

        // Loop over each number in the string and calculate the current sum
        for (var i = 0; i <= 8; i++) {
            var minus = i-1;
            var plus = i+1;
            currentNumber = value.charAt(i);
            currentMultiplier = multipliers[plus];
            currentSum += (currentNumber * currentMultiplier);
            console.debug("i is " + i + " & current Num: " + currentNumber + " plus current multi: " + currentMultiplier + " plus " + currentSum);
        }

        var remainder = currentSum % 11;
        var total = 11 - remainder;
        console.debug(currentSum);

I don't know if the minus and plus vars are necessary but they're something I tried while trying to fix the NaN issue. A typical console debug line looks like this:

i is 0 & current Num: 1 plus current multi: 10 plus NaN 

I've also tried this with the same NaN result:

currentSum = currentSum + (currentNumber * currentMultiplier);
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1 回答 1

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var currentSum, currentNumber, currentMultiplier = 0;

不正确,仅初始化 currentMultiplier。

它应该是

var currentSum, currentNumber, currentMultiplier;
currentSum =  currentNumber = currentMultiplier = 0;

演示:http: //jsfiddle.net/46dD5/

于 2013-07-24T13:16:53.163 回答