javascript - Double curly braces {{}} problem in angular.js

Question

<p ng-controller="listCtrl">
    <h1>这是列表页面</h1>
    <ul>
        <li ng-repeat="item in myList"><a href="#/myDetail/{{$index}}">{{item}}</a></li>
        <li ng-repeat="item in myList"><button ng-click="jump('/myDetail/'+$index)">{{item}}</button></li>
    </ul>

</p>

As the title says, in the above code, I need to get the $index value as a parameter. I need to add {{}} to the first li to get the value, but there is no need to add it to the second li; how should I do this? distinguish? ?

Answer 1

In order to parse data in native HTML, you need to use {{}} to bind data, but there is no need for this behind the ng command.

Answer 2

{{ $var }} wrapped template variable , used when directly output the variable value without additional parsing (such as filter processing, as an instruction parameter, as a function parameter), otherwise, ng -click="jump('/myDetail/'+ $index)" is the parameter called in the command.

Answer 3

The simple criterion is

• If the type assigned to the current attribute is a literal type, such as an attribute in an html template, or an attribute with @ as a modifier in a directive, then if you do not add double curly brackets when assigning the value, it will be a literal value. To calculate, if you want to parse it as a variable, you need to add double curly braces.

• If the type assigned to the current attribute is a non-string type, such as various built-in instructions in the angular template, or attributes modified with <, =, & in the instructions, then the assignment will be as follows The syntax rules of js are parsed. In this case, there is no need to add curly brackets.

Answer 4

First explain the two types in Angular:

Template: The format is {{...}}, which is essentially a string, and will be expanded into a recognizable string text by the parsing engine
Expression: code that can be run directly, basically the same as JS writing, except All this omitted.

Then you can refer to the context to determine whether you are writing a JS-like part or writing a string literal, so that it is easy to judge whether you need a template or an expression.