移动Safari iOS 6上的奇怪JavaScript行为 [英] Strange JavaScript behaviour on mobile Safari iOS 6

问题描述

我遇到了一个非常非常奇怪的JS问题，只能在iOS 6上的Mobile Safari浏览器上进行复制。
问题在于将一个给定值格式化为价格的函数，通过将数字拆除为2位小数，并在数字前面添加货币。这是功能。我稍后将解释如何重现该错误。

I ran into a very very very strange JS issue that is reproducing only on Mobile Safari browser on iOS 6. The issue is in a function that formats a given value to a price, by stripping down the number to 2 decimals and adds the currency in front of the number. Here are the functions. I will explain later on how to reproduce the bug.

formatCurrency = function(value, currency, fixedPrecision, colourize, blankIfZero) {
    var text;

    if (blankIfZero && (Math.abs(value) < 0.01 || value === undefined)) {
         return "";
    }

    if (fixedPrecision) {
        text = currency + Math.abs(value).toFixed(2);
    } else {
        text = currency + roundTo2Decimals(Math.abs(value));
    }

    if (value < 0) {
        text = "-" + text;
    }

    if (colourize) {
        var colorClass = (value < 0 ? "negative" : "positive");
        text = "<span class='" + colorClass + "'>" + text + "</span>";
    }

    return text;
};

roundTo2Decimals = function(value) {
    var sign = value < 0 ? -1 : 1;
    return Math.round(Math.abs(value) * 100.0)/100.0 * sign;    
};

如果我一遍又一遍地运行formatCurrency函数（例如在setInterval中）值（让我们说值= 1;以及货币=英镑）你会注意到每次800-1000次迭代，函数返回的值包含一个负数：GBP-1而不是GBP1。这个问题非常烦人我在JS函数中没有发现任何问题。

If I run the the formatCurrency function over and over again (within a setInterval for example) with the same value (lets say value=1; and currency="GBP") you will notice the once every 800-1000 iterations the value return by the function contains a negative amount: GBP-1 instead of GBP1. This issue is very annoying i I did not found any issue within the JS functions.

我设法解决这个问题...但我很好奇这是什么问题有了这个实现。

I manage to fix the issue ... but I'm curious what is the issue with this implementation.

我错过了什么？

推荐答案

我想;

text = - + String（text）;

text = "-" + String(text);

是问题。

我也常常在Safari中浏览iOS6相关的bug。如果我们希望它能够顺利执行，那JS似乎应该更加清洁！

Me too have been surfing around a lot for iOS6 related bugs in Safari. It seems the JS should be lot more cleaner if we want it to execute smooth!

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