how to query in windows js

JavaScript
function getQueryStringValue (key) {  
  return decodeURIComponent(window.location.search.replace(new RegExp("^(?:.*[&\\?]" + encodeURIComponent(key).replace(/[\.\+\*]/g, "\\$&") + "(?:\\=([^&]*))?)?.*$", "i"), "$1"));  
}  

// Would write the value of the QueryString-variable called name to the console  
console.log(getQueryStringValue("name")); 

Source

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