Question: Does anyone know how to check if jquery has been loaded (with javascript) then load it if it hasnt been loaded.

something like

```
if(!jQuery) {
    //load jquery file
}

```

Answer: 
You can check if jQuery is loaded or not by many ways such as:  

```
if (typeof jQuery == 'undefined') {

    // jQuery IS NOT loaded, do stuff here.

}

```

```
if (typeof jQuery == 'function')
//or
if (typeof $== 'function')

```

```
if (jQuery) {
    // This will throw an error in STRICT MODE if jQuery is not loaded, so don't use if using strict mode
    alert("jquery is loaded");
} else {
    alert("Not loaded");
}

```

```
if( 'jQuery' in window ) {
    // Do Stuff
}

```

Now after checking if jQuery is not loaded, you can load jQuery like this:  

> 
> *Although this part has been answered by many in this post but still
>  answering for the sake of completeness of the code*
> 
> 
> 

```
    // This part should be inside your IF condition when you do not find jQuery loaded
    var script = document.createElement('script');
    script.type = "text/javascript";
    script.src = "http://code.jquery.com/jquery-3.3.1.min.js";
    document.getElementsByTagName('head')[0].appendChild(script);

```
```
<script>
if (typeof(jQuery) == 'undefined'){
        document.write('<scr' + 'ipt type="text/javascript" src=" https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></scr' + 'ipt>');
}
</script>

```