jsCalc is a simple, completely vanilla JavaScript calculator library that allows you to stylistically implement it however you want. Included is an example implementation using Bootstrap3.
Initialization is simple:
var calc = jsCalc();
The library relies on a few selectors prefixed with 'jsc_'.
For your number buttons:
<div class="jsc_calculator_button">
<button class="jsc_number_button">1</button>
</div>
Similarly, for operator buttons:
<div class="jsc_calculator_button">
<button class="jsc_operator_button">*</button>
</div>
For the 'clear' button:
<a id="jsc_clear_button">clear</a>
The 'equals' button is a little different because it is checked as an operator right now, so it relies on 'jsc_calculator_button':
<div class="jsc_calculator_button">
<a id="jsc_equals_button">=</a>
</div>
This is a work in progress and any feedback and contributions are welcome, or if you'd just like to see a feature and don't want to contribute feel free to drop an issue in the issues section. Thanks!