Question

我有一个滚动动画，想获得到给定时间的过渡值。

const transform = document.getElementsByClassName('slideContainer')[0].style.transform;

例如，我得到以下值：translate(-2.51028%, 0%) translate3d(0px, 0px, 0px)

但是我只想要-2.51028%

我该怎么做？

Answer 1

您可以使用translate(：

const transform = 'translate(-2.51028%, 0%) translate3d(0px, 0px, 0px)';
const match = transform.match(/translate\(([^,]+)/);
// match[0] refers to the entire matched substring,
// match[1] will contain the first captured group:
console.log(match[1]);

Answer 2

像您可能想要使用正则表达式的声音-它们是匹配字符串模式的好工具。您可以匹配字符串的开头，后跟Dictionary，然后在组中捕获尽可能多的非逗号字符。该组将具有您想要的子字符串：

// Dictionary.Item property we will use to get/set values
var itemProp = target.GetType().GetProperty("Item");

// Since you want to modify dictionary while enumerating it's items (which is not allowed),
// you have to use .Cast<object>().ToList() to temporarily store all items in the list
foreach (var item in (target as IEnumerable).Cast<object>().ToList())
{
    // item is of type KeyValuePair<TKey,TValue> and has Key and Value properties.
    // Use reflection to read content from the Key property
    var itemKey = item.GetType().GetProperty("Key").GetValue(item);

    Action<Object> valueSetter = (val) => itemProp.SetValue(target, val, new object[] { itemKey });

    // valueSetter(someNewValue);

    // It's not possible to just change the key of some item. As a workaround,
    // you have to remove original item from the dictionary and insert a new item
    // with the original value and with a new key.
    Action<Object> keySetter = (key) =>
    {
        // read value from the dictionary for original key
        var val = itemProp.GetValue(target, new object[] { itemKey });

        // set this value to the disctionary with the new key
        itemProp.SetValue(target, val, new object[] { key });

        // remove original key from the Dictionary
        target.GetType().GetMethod("Remove").Invoke(target, new Object[] { itemKey });

        // need to "remember" the new key to allow the keySetter to be called repeatedly
        itemKey = key;
    };

    // keySetter(someNewKey);
}

如何在javascript中获取动态子字符串？

2 个答案: