Inconsistent documentation or behaviour of vm.$watch

[atleta]

Vue.js version

2.0.2

The following code produces the following error on the console:

const app = new Vue({
    el: '#app',
    // template: '#app-template',
    data: {
        height: 0,
        weight: 0,
    },
// ....
});
app.$watch('weight + height', function () {
  // do something
});

vue.js:2611[Vue warn]: Failed watching path: "weight + height" Watcher only accepts simple dot-delimited paths. For full control, use a function instead.

OTOH the documentation (https://vuejs.org/v2/api/#vm-watch) explicitely states that it's a valid syntax. It even has the same example.

[defcc]

Thanks @atleta , the document needs to be updated

[yyx990803]

moved to vuejs.org

[defcc]

A PR created. vuejs/v2.vuejs.org#570 .

[lopugit]

I got this error when trying to watch a literal path 'some.path.with a space delimited property path.value', do spaces still work? I thought this should act the same as any square bracket property access syntax, such as some.path['with a space delimited property path'].value ?