javascript - 无法将 NaN 替换为 0 - 尝试了 rapply

Question

似乎无法将 Not a Number NaN 错误替换为 0。尝试使用 rapply 但对我不起作用。

window.onload = function () {
    var first = document.getElementById('firstFieldId'),
        second = document.getElementById('secondFieldId'),
        third = document.getElementById('thirdFieldId'),
        fourth = document.getElementById('fourthFieldId');

    first.onkeyup = function () {
        var value;

        // Get the value and remove the commas
        value = first.value.replace(/,/g, "");

        // Make it a number
        value = parseInt(value, 10);

        // Add one to it
        ++value;

        // Turn it back into a string
        value = String(value);

        // Put it in the other text box, formatted with commas
        second.value = numberWithCommas(value);
    };
    third.onkeyup = function () {
        var value;

        // Get the value and remove the commas
        value = third.value.replace(/,/g, "");

        // Make it a number
        value = parseInt(value, 10);

        // Add one to it
        ++value;

        // Turn it back into a string
        value = String(value);

        // Put it in the other text box, formatted with commas
        fourth.value = numberWithCommas(value);
    };

    function numberWithCommas(x) {
        return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    }
};

做了一个 JSFiddle http://jsfiddle.net/7r5SF/2/ - 如果您在第一个或第三个字段中输入一个数字，然后清除它，第二个或第四个字段将显示为 NaN...它需要说 0 !

任何帮助都会很棒!

Answer 1

替换

++value;

与

value = isNaN(value) ? 0 : value+1

JSFiddle