最简单的方式理解Vue的自定义指令

<div id="hook-arguments-example"
     v-demo:hello.a.b="message"
     v-color-swatch="bgColor"
        ></div>

Vue.directive(‘demo‘, {
    bind: function (el, binding, vnode) {
        var s = JSON.stringify; // 用于从一个对象解析出字符串
        el.innerHTML =
            ‘name: ‘ + s(binding.name) + ‘<br>‘
            +‘value: ‘ + s(binding.value) + ‘<br>‘
            +‘expression: ‘ + s(binding.expression) + ‘<br>‘
            +‘argument: ‘ + s(binding.arg) + ‘<br>‘
            +‘modifiers: ‘ + s(binding.modifiers) + ‘<br>‘
            + ‘vnode keys: ‘ + Object.keys(vnode).join(‘, ‘)
    }
});

Vue.directive(‘color-swatch‘, function (el, binding) {
    el.style.backgroundColor = binding.value;
});

new Vue({
    el: ‘#hook-arguments-example‘,
    data: {
        message: ‘hello!‘,
        bgColor: ‘red‘
    }
});