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Watch in Vue.js can be used to listen for changes in data properties and perform operations. The syntax is: watch(expression, callback, options). It supports using strings or functions to monitor data attributes, and calls callback functions when they change. You can configure whether to call immediately, whether to monitor deeply, and whether to update synchronously through options.
Usage of watch in Vue.js
Watch in Vue.js is a reactive API that can Lets you listen for changes in data properties and perform actions based on those changes.
Syntax
<code class="js">watch(expression, callback, options)</code>
Parameters
Example
<code class="js">// 使用字符串 watch('message', function (newValue, oldValue) { console.log(`Message changed from "${oldValue}" to "${newValue}".`); }); // 使用函数 watch(function () { return this.count; }, function (newValue, oldValue) { console.log(`Count incremented from ${oldValue} to ${newValue}.`); });</code>
Options
Usage scenarios
Common scenarios for using watch include:
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