Squarespace Parse Query String and Prefill Email Field in Contact Form

injected.snippet.js

function parseSearchString () {
  var qs = window.location.search
  qs = qs.replace(/^\?/,'')
  var parts = qs.split('&')
  var params = {}
  parts.forEach(function (part) {
    var pair = part.split('=')
    params[pair[0]] = decodeURIComponent(pair[1])
  })
  return params
}

window.onload = function () {
  var qs = parseSearchString()
  if (qs.SQF_USER_EMAIL) {
    var el = document.querySelectorAll('input[name=email]')
    if (!el.length) return
    el[0].value = qs.SQF_USER_EMAIL
  }
}