Question

我试图避免在dom-repeat中多次调用相同的函数。

示例：

<template is="dom-repeat" items="..." as="column">
  <template result="_myFunction(column, index)">
    <div>Primary: [[result.primary]]</div>
    <div>Secondary: [[result.secondary]]</div>
    ...
  </template>
</template>


...
_myFunction(column, index) {
  return { primary: "1", secondary: "2", ......}
}

但我无法找到正确的方法，因为我正在_myFunction(column, index)的所有<div>中呼叫$hosts = array ( 0 => 'example/search?results1', 1 => 'thisone/search?results2', 2 => 'thesetoo/search?results3' ); $counts = array ( 0 => '3', 1 => '5', 2 => '7' ); $results =array(); foreach ( $counts as $count ) { $key_of_count = array_search( $count, $counts ); for ($i=0; $i < (int)$count; $i++) { $results[$key_of_count][] = $hosts[$key_of_count]; } } echo "<pre>"; print_r($results); echo "</pre>";。

如何避免多次调用该函数？

Answer 1

尝试使用以下代码，其中带有DOM重复的聚合物自定义元素的工作示例，希望这对您有用，

<dom-module id="your-template-container">
    <template>
        <template is="dom-repeat" items="{{data}}" as="column">
            <div>Primary: [[column.primary]]</div>
            <div>Secondary: [[column.secondary]]</div>
        </template>
    </template>

    <script>
        Polymer({
            is: 'your-template-container',
            ready: function() {
                // Sample object data is below
                this.data = [
                    {primary: 1, secondary: 2},
                    {primary: 1, secondary: 2},
                    {primary: 1, secondary: 2}
                ];
            }
        });
    </script>

</dom-module>

<!-- THE FOLLOWING WILL RENDER YOU POLYMER CUSTOM ELEMENT WITH DOM REPEAT-->
<your-template-container></your-template-container>

Answer 2

我找到了一种避免使用缓存多次调用_myFunction的方法：

Before the `dom-repeat`: 
  execute the function 
  cache the result in an object

In the `dom-repeat`
  use the cached-object to retrieve the value

奖励：使用备忘录也可能有效

聚合物在模板内绑定功能结果

2 个答案: