Change div content in HTML5 Custom Data Attributes

Question

I declare a following div in file1.html to draw a nice gauge. The div uses some HTML5 Custom Data Attributes as follow:

<div class="gauge" id="meter1" data-settings='
   {"value": 7,
    "min": 0,
    "max": 50,
    "threshold": [
      {"from": 25, "to": 50, "color": "blue", "label": "Warning"},
      {"from": 0, "to": 25, "color": "orange", "label": "Critical"}
        ]
    }'></div>

Now in Javascript, how do I recall the div and set new number for the "value" attribute and "threshold" attribute? Thanks

Answer 1

You can use document.querySelector with JSON.parse

 const gauge = document.querySelector('#meter1'); console.log(JSON.parse(gauge.dataset.settings).threshold)

 <div class="gauge" id="meter1" data-settings=' {"value": 7, "min": 0, "max": 50, "threshold": [ {"from": 25, "to": 50, "color": "blue", "label": "Warning"}, {"from": 0, "to": 25, "color": "orange", "label": "Critical"} ] }'></div>

Answer 2

You can use following functions to fulfill your task:

• element.getAttribute to get the values inside the attribute
• element.setAttribute to set the values inside the attribute
• JSON.stringify and JSON.parse to work with JSON

Check the code below.

 var meter1 = document.getElementById("meter1") var dataSettings = JSON.parse(meter1.getAttribute("data-settings")) dataSettings.value = 8 dataSettings.min = 5 meter1.setAttribute("data-settings", JSON.stringify(dataSettings)) console.log(meter1.getAttribute("data-settings"))

 <div class="gauge" id="meter1" data-settings=' {"value": 7, "min": 0, "max": 50, "threshold": [ {"from": 25, "to": 50, "color": "blue", "label": "Warning"}, {"from": 0, "to": 25, "color": "orange", "label": "Critical"} ] }'></div>