5 examples of 'jquery if variable exists' in JavaScript

50
function isVarDefined(variable) {
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    return typeof variable !== 'undefined';
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}

12
function getQueryVariable(variable) {
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  let query = window.location.search.substring(1);
14
  let vars = query.split("&");
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  for (let i = 0; i < vars.length; i++) {
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    let pair = vars[i].split("=");
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    if (pair[0] == variable) { return pair[1]; }
18
  }
19
  return (false);
20
}

589
function hasJQueryData(object) {
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  var data = evalJQueryData(object);
591
  for (var x in data) {
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    if (data.hasOwnProperty(x)) {
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      return data;
594
    }
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  }
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};

6
function isDefined (variable) {
7
  return !(variable === undefined || variable === '' || variable === null)
8
}

23
function isNotEmpty(variable) {
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    return (undefined !== variable && null !== variable);
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}