What should I do if the uniapp filtering attribute does not take effect on iOS?

With the popularity of mobile applications, more and more developers are turning their attention to uniapp, a cross-platform development tool. It is based on the Vue.js framework, which can achieve the effect of writing once and running on multiple platforms. However, when using uniapp to develop mobile applications, you will also encounter some problems. Today, we will discuss the problem that the uniapp filtering attribute does not take effect on iOS.

1. Problem phenomenon

In uniapp, we can use filters to format our data. For example, using {{time | dateFormat}} in the template can convert time into the date format we want. The code is as follows:

<template>
  <view>{{ date | dateFormat }}</view>
</template>

<script>
  export default {
    data() {
      return {
        date: '2022-01-01 12:00:00'
      }
    },
    filters: {
      dateFormat(val) {
        return val.split(' ')[0]
      }
    }
  }
</script>

When running on the Android side, "2022-01-01" can be output normally. But on the ios side, the original "2022-01-01 12:00:00" will be output, and the filter does not seem to take effect.

2. Analysis of reasons

After investigation and analysis, we found that this problem is caused by the JS engine on the ios side improperly handling regular expressions in ES6 syntax. Specifically, Said that the problem lies in the way the uniapp filtering attribute is implemented.

In Vue.js, filters are implemented through Vue.prototype.$filter. In uniapp, this global variable is defined in uni-app/dist/vue.runtime.esm.js. In Vue.js, there is another way to implement filters, which is to use the Vue.component() method to pass an object that contains a filters property. This method is also applicable in uniapp, but the display effect on the iOS side is different from the above method and can be output normally.

3. Solution

Now that we find that the problem lies in the implementation of the uniapp filtering attribute, the solution is ready to come out. For this problem, we have the following two solutions:

(1) Use the Vue.component() method to define the filter

<script>
  export default {
    data() {
      return {
        date: '2022-01-01 12:00:00'
      }
    },
    created() {
      Vue.component('dateFormat', {
        filters: {
          dateFormat(val) {
            return val.split(' ')[0]
          }
        }
      })
    }
  }
</script>

In the above code, we use Vue.component () method to define filters. After testing, this method can output normally on the ios side.

(2) Use regular expressions to solve the problem

In uniapp development, we can also use regular expressions to solve the problem that the filter does not take effect on the ios side. We can use the replace() method in the filter to replace non-numeric characters with null characters and then output a string in the specified format. The code is as follows:

<script>
  export default {
    data() {
      return {
        date: '2022-01-01 12:00:00'
      }
    },
    filters: {
      dateFormat(val) {
        return val.replace(/[^\d]/g, '').substring(0, 8)
      }
    }
  }
</script>

In this code, we use the regular expression /¹/g to match non-numeric characters and replace() method to replace it with the null character. Finally, use the substring() method to get the string output in the specified format. Similarly, after testing, this method can also output normally on the ios side.

In short, in uniapp development, there is no need to panic when encountering such problems. You only need to deeply analyze the nature of the problem and adopt correct and effective solutions, and the problem will be solved.

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