Select option element after event on amp

user_8266001 0
Viewed 2678

I want to automatically select one of the options of the second & third dropdowns automatically once the user changes the first one.

<body>
  <h1>Hello AMPHTML World!</h1>
  <label for="color">Color</label>
  <select name="color" id="color" on="change:size.focus">
    <option disabled selected></option>
    <option value="blue">blue</option>
    <option value="red">red</option>
    <option value="green">green</option>
  </select>
  <label for="size">Size</label>
  <select name="size" id="size">
    <option disabled selected></option>
    <option value="small">small</option>
    <option value="medium">medium</option>
    <option value="big">big</option>
  </select>
  <label for="material">Material</label>
  <select name="material" id="material">
    <option disabled selected></option>
    <option value="paper">paper</option>
    <option value="plastic">plastic</option>
    <option value="wood">wood</option>
  </select>
</body>

So far, I only found the action focus but it would be great to have something like select(value=small). Any idea or workaround? Thanks!

amp-html
2 Answers

You can achieve this by using amp-bind. When you select an option in the first dropdown set a state with desired value. For demonstration, I created a state for storing a mapping as to which value is to be set corresponding to the selection as follows:

  <amp-state id="mapping">
  <script type="application/json">
   {
      "blue" : "small",
      "red" : "medium",
      "green" : "big"
   }
  </script>
  </amp-state>

Then we have to set a state corresponding to selection in the dropdown as follows:

<select name="color" id="color" on="change:AMP.setState({ val : mapping[event.value] })">

Now we have to bind the selected attribute in each option in the second dropdown to evaluate to true if the corresponding value is set to val as follows:

  <select name="size" id="size">
    <option disabled selected></option>
    <option value="small" [selected]=" val == 'small' ">small</option>
    <option value="medium" [selected]=" val == 'medium' ">medium</option>
    <option value="big" [selected]=" val == 'big' ">big</option>
  </select>

NOTE: Do not forget to add the amp-bind script

<script async custom-element="amp-bind" src="https://cdn.ampproject.org/v0/amp-bind-0.1.js"></script>`
user_43801370

There is no action and event for select the option value, You can use amp-bind for that

Here is working code 

<!doctype html>
<html ⚡>
 <head>
   <meta charset="utf-8">
   <link rel="canonical" href="amp-bind.html">
   <meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
   <style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
   <script async src="https://cdn.ampproject.org/v0.js"></script>
    <script async custom-element="amp-bind" src="https://cdn.ampproject.org/v0/amp-bind-0.1.js"></script>
  
 </head>
 <body>
 <label for="color">Color</label>
  <select name="color" id="color" on="change:AMP.setState({ optionValue: true })">
    <option disabled selected></option>
    <option value="blue">blue</option>
    <option value="red">red</option>
    <option value="green">green</option>
  </select>
  <label for="size">Size</label>
  <select name="size" id="size">
    <option disabled selected></option>
    <option [selected]="optionValue" value="small">small</option>
    <option value="medium">medium</option>
    <option value="big">big</option>
  </select>
  <label for="material">Material</label>
  <select name="material" id="material">
    <option disabled selected></option>
    <option [selected]="optionValue" value="paper">paper</option>
    <option value="plastic">plastic</option>
    <option value="wood">wood</option>
  </select>
  
 </body>
</html>

Another way to do this by using a trick in html without amp-bind

Here is working url

<!doctype html>
<html ⚡>
 <head>
   <meta charset="utf-8">
   <link rel="canonical" href="amp-bind.html">
   <meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
   <style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
   <script async src="https://cdn.ampproject.org/v0.js"></script>
    <script async custom-element="amp-bind" src="https://cdn.ampproject.org/v0/amp-bind-0.1.js"></script>
  
 </head>
 <body>
 <label for="color">Color</label>
  <select name="color" id="color" on="change:fsize.hide,size.show,fmaterial.hide,material.show">
    <option disabled selected></option>
    <option value="blue">blue</option>
    <option value="red">red</option>
    <option value="green">green</option>
  </select>
  <label for="size">Size</label>
  <select id="fsize">
  <option disabled selected></option>
  </select>
  <select hidden name="size" id="size">
   <option value="small">small</option>
    <option value="medium">medium</option>
    <option value="big">big</option>
  </select>
  <label for="material">Material</label>
   <select id="fmaterial">
  <option disabled selected></option>
  </select>
  <select hidden name="material" id="material">
   <option value="paper">paper</option>
    <option value="plastic">plastic</option>
    <option value="wood">wood</option>
  </select>  
 </body>
</html>

user_56350980
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