Printing a JS variable in a value=“” attribute

问题

I'm trying to implement a Paypal button with a dynamic value. When I enter, for example, value="300.00", the button works fine.

However, if I do it my way, the button doesn't work properly. The variable price is the JS variable that holds the information I need to put into the Paypal button.

Here's the line of code at fault:

<input type="hidden" name="amount" value="<script>document.write(price)</script>.00">

回答1:

In javascript:

document.write('<input type="hidden" name="amount" value="' + price + '">')

Or better yet

var div = document.createElement('div');
div.innerHTML = '<input type="hidden" name="amount" value="' + price + '">';
document.body.appendChild(div);

DEMO

回答2:

It doesn't work because you have unclosed tags.
Notice here that you opened another tag without closing the other tag.

<*input type="hidden" name="amount" value="<*script

To achieve what you want, you need to write the entire block using JS

<script>
document.write('<input type="hidden" name="amount" value="' + price + '.00">');
</script>

回答3:

document.getElementsByName('amount')[0].value = price;

This will find the "button" and set its value to the value of the price variable. I assume that the "button" already is somewhere on the page.

来源：https://stackoverflow.com/questions/4812198/printing-a-js-variable-in-a-value-attribute