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How to check if jQuery is loaded and what version?

检查是否装满JQuery的最佳方式是什么?

Answer 1

if (typeof jQuery ===  undefined ) {
  // jQuery is NOT available
} else {
  // jQuery is available
}

Answer 2

参看。

<><><>>Method 1:>>>

if (jQuery) {  
    // jQuery is loaded  
} else {
    // jQuery is not loaded
}

<><><>>Method2:>>>

if (typeof jQuery ==  undefined ) {  
    // jQuery is not loaded  
} else {
    // jQuery is loaded
}

<><><><><>> > >>

try
{
     var jqueryIsLoaded = jQuery;
     jQueryIsLoaded = true;
}
catch(err)
{
     var jQueryIsLoaded = false;
}

if(jQueryIsLoaded) 
{
}
else
{
}

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