Simple Javascript Execution

 

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  • Is there an “exists” function for jQuery? 36 answers

    • 要检查页面中是否存在元素，可以选择它，然后检查length属性（如果使用jQuery）或者它为null（如果使用普通的JS）： 

    // jQuery
if ($('.site-header__cart-indicator').length)
  window.setTimeout(redirectCheckout, 2000);

// plain JS
if (window.querySelector('.site-header__cart-indicator'))
  window.setTimeout(redirectCheckout, 2000);

    Well, for one thing you have a quoting error: 

    "<span class="site-header__cart-indicator"></span>"

    should be: 

    '<span class="site-header__cart-indicator"></span>'

    But more to the point , this condition makes no sense. That string would never be in the location (the current URL). It would be on the page.

    Even though your code currently has no jQuery, you do specifically request its use. In which case you can select for that element and see if there are any matches. Something like this: 

    if ($('span.site-header__cart-indicator').length > 0)
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