A guide on trimming content with v-if in Vue.js

Recently, I attempted to trim the response value within a Vue condition.

I require this functionality to apply the condition when the value is null or empty.

<li v-if="item[0].otrodl4.trim() == ''" class="progress-step">

Unfortunately, I encountered an error.

vue.js:597 [Vue warn]: Error in render: "TypeError: Cannot read property 'trim' of null"

The issue lies in some values containing only whitespace, which should be treated as null or empty.

For example:

https://i.sstatic.net/2eul8.png

I attempted to use filters, but still received the same error.

Thank you for reading.

Best regards.

javascriptvue.js

Answer №1

Give this a shot:

!item || !item[0] || !item[0].otrodl4 || item[0].otrodl4.trim() == ''

Essentially, you need to ensure that item is not undefined or null. Also, make sure that the first element of the array exists and has a property called otrodl4.

Answer №2

Give this a shot:

item[0] && item[0].otrodl4.trim() == ''

Therefore, the condition item[0].otrodl4.trim() == '' is only evaluated if there is a value present in the 0 index of the item array.

This is referred to as a short-circuit condition and you can delve deeper into it here.

Answer №3

I utilized the trim() function and it worked perfectly. You should give it a try and see if it can assist you as well.

<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.3.0/vue.js"></script>
</head>
<body>
<div id="app">
<!--if only space in text it will display "hello space" else no dsplay.  -->
<p v-if="text.trim()==''">hello whitespace {{ text | trim }}</p>

</div> 
<script>
new Vue({

el: '#app',
  
  data: function() {
    return {
        text: ' '    // added only a space
    }
  }
  
 

});
</script> 
         
</body>
</html>

Answer №4

When encountering a TypeError, it means that the variable being manipulated may not be what the developer expected it to be.

Issues like this often occur in languages without strong typing mechanisms.

To avoid such errors, it is recommended to use optional chaining to verify the variable's type before operating on it.

With the introduction of ES2020, optional chaining has become a useful tool for type checking.

For instance,

v-if="!!item?.[0]?.otrodl4?.trim && item?.[0]?.otrodl4?.trim() == ''"

The use of !! helps convert falsy values like null, undefined, or empty strings to false.

By confirming that the otrodl4 property has a method trim before calling it, we can prevent TypeErrors from occurring.

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