Home >Web Front-end >JS Tutorial >Things to note when using v-bind to bind classes in Vue.js
Preface
In Vue.js version: 1.0.27, when using the V-bind instruction in Vue.js to bind class and style, Vue.js has enhanced it. In addition to strings, expression results can also be objects or arrays.
I tested it here and found the following problem:
If you use object syntax to bind a class, the class name must be added with quotation marks, representing the corresponding style, otherwise it will be regarded as an attribute of the object, causing an initialization error.
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Document</title> <script src="http://cdn.bootcss.com/vue/1.0.27/vue.js"></script> <style> .static { font-size: 120px; width: 600px; margin: 0 auto; background-color: yellow; height: 120px; line-height: 120px; text-align: center; } .class-a { color: #FF0000; } .class-b { text-decoration: underline; } </style> </head> <body> <div id="app"> <div v-bind:class="classObject"> 关于class的绑定 </div> </div> <script> var vm = new Vue({ el: '#app', data: { classObject: { //'class-a',不能写成class-a(不带引号);这里的classObject是js对象,而class-b是代表的是一个样式,所以必须写成'class-a',用引号括起来。 //否则这里的class-a只能代表classObject的一个属性名称而已,这样vuejs在初始化时,会报错。 'class-a':false, 'class-b': true } } }); </script> </body> </html>
Reference materials:
Vue.js official website----http://cn.vuejs.org/guide/class-and-style.html
Supplement:
Here, I feel that the classObject in the code is a bit like a hash table. The key is a style class, and the value is a boolean type value.
Get and change the class-a value in the classObject object from the console, see the picture below:
See the operation in the console, let me I feel that classObject is indeed a bit like a hash table type. In order to confirm this, you can take a look at the source code (ps: I didn’t look at it myself).
In Vue.js1.0.19, the author added some syntax to it. Object syntax can also be used in arrays:
Above, you can add or not add quotes for classA. The following is your own test code.
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Document</title> <script src="http://cdn.bootcss.com/vue/1.0.27/vue.js"></script> <style> .static { font-size: 120px; width: 600px; margin: 0 auto; background-color: yellow; height: 120px; line-height: 120px; text-align: center; } .class-a { color: #FF0000; } .classB { text-decoration: underline; } .classC{ text-shadow: 2px 2px 4px #000000; } </style> </head> <body> <div id="app"> <!-- 两种绑定:加引号和不加引号,都可以 --> <div v-bind:class="[classA, { 'classB': isB, 'classC': isC }]">class绑定</div> <div v-bind:class="[classA, { classB: isB, classC: isC }]">class绑定</div> </div> <script> var vm = new Vue({ el: '#app', data: { classA: 'class-a', isB: true, isC: true } }); </script> </body> </html>
Summary
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