PayPal Smart Payment Buttons error paypal.Buttons is not a function - php

Question

I am integrating Smart Payment Buttons in my website, before it works properly, but earlier today, I am getting these errors
I loaded paypal SDK before I even loaded the paypal.Buttons().render() function which is inside my paypal.js file
<script src="https://www.paypal.com/sdk/js?client-id=<MY_CLIENT_ID_HERE>&currency=PHP"></script>
<script type="text/javascript" src="paypal.js"></script>
this is the content of my paypal.js file
paypal.Buttons({
createOrder : function(data, actions){
return actions.order.create({
purchase_units : [{
amount : {
value : amount_to_pay
}
}],
application_context: {
shipping_preference: "NO_SHIPPING",
},
country_code : "PH"
})
},
style: {
color: 'gold',
shape: 'rect',
label: 'buynow',
size: 'responsive',
branding: true
},
onApprove: function(data, actions) {
// Capture the funds from the transaction
return actions.order.capture().then(function(details) {
return fetch('/pay-with-pp', {
method: 'post',
headers: {
'content-type': 'application/json'
},
body: JSON.stringify({
orderID: data.orderID,
product_id : product_id,
_token : token
})
}).then(function(res){
alert('Payment has been made! Please see the delivery status on orders page!');
window.location.href = redirect_url
});
});
},
}).render('#paypal-button-container');

Answer 1

I analyzed the errors carefully and found out the solution.
I added a data-namespace attribute to the script tag that loads the SDK
<script src="https://www.paypal.com/sdk/js?client-id=AaJMejIDjhumOr48XsycjfvQegxAku1dHdrA0DNfkqFSg7bFFkpJTnnwyaLIGUFsPijWx1g51gxp9F-5&currency=USD" data-namespace="paypal_sdk"></script>
then use the value of data-namespace in my paypal.js file
so instead of
paypal.Buttons().render()
i used
paypal_sdk.Buttons().render()
and it works!

Answer 2

(I got this error in ReactJs)
Make sure you're loading the <script> tags properly - to which I mean, don't delay their loading by adding things like the defer attribute, otherwise paypal.Buttons() is called before the script tags are called, hence the error.
I don't know if 2 years down the line since this question was asked whether my answer will be at all helpful.