When working with Vue.js, we can easily access the value after modification within watchers using the following syntax:
watch: function(valueAfterModification){
// ......
}
But what about getting the value before it's modified?
PS: The official documentation doesn't provide any information on this here
To access the previous value in the watcher function, simply add an additional parameter for old value as shown below:
watch: {
value: function(newVal, oldVal) {
//oldVal represents the value before any changes
alert('newVal ' + newVal + ' oldVal ' + oldVal)
}
}
For a demonstration, check out this sample fiddle here.
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