I am new to front end development and I have a requirement of using bootstrap modal.

I tried copying the bootstrap css and js code for modal and kept in my css file and kept the javascript in script tag and tried using the modal. But I am not getting the pop up on clicking button. CSS is getting applied but js part is not working. 

Am I missing anything here? 

This is bootstrap modal js code -

```
<script type="text/javascript">

'use strict';

// MODAL CLASS DEFINITION
// ======================

var Modal = function (element, options) {
this.options   = options
this.$element  = $(element)
this.$backdrop =
this.isShown   = null

if (this.options.remote) {
this.$element
.find('.modal-content')
.load(this.options.remote, $.proxy(function () {
this.$element.trigger('loaded.bs.modal')
}, this))
}
}

Modal.DEFAULTS = {
backdrop: true,
keyboard: true,
show: true
}

Modal.prototype.toggle = function (_relatedTarget) {
return this[!this.isShown ? 'show' : 'hide'](_relatedTarget)
}

Modal.prototype.show = function (_relatedTarget) {
var that = this
var e    = $.Event('show.bs.modal', { relatedTarget: _relatedTarget })

this.$element.trigger(e)

if (this.isShown || e.isDefaultPrevented()){ return }

this.isShown = true

this.escape()

this.$element.on('click.dismiss.bs.modal', '[data-dismiss="modal"]', $.proxy(this.hide, this))

this.backdrop(function () {
var transition = $.support.transition && that.$element.hasClass('fade')

if (!that.$element.parent().length) {
that.$element.appendTo(document.body) // don't move modals dom position
}

that.$element
.show()
.scrollTop(0)

if (transition) {
that.$element[0].offsetWidth // force reflow
}

that.$element
.addClass('in')
.attr('aria-hidden', false)

that.enforceFocus()

var e = $.Event('shown.bs.modal', { relatedTarget: _relatedTarget })

transition ?
that.$element.find('.modal-dialog') // wait for modal to slide in
.one($.support.transition.end, function () {
that.$element.focus().trigger(e)
})
.emulateTransitionEnd(300) :
that.$element.focus().trigger(e)
})
}

Modal.prototype.hide = function (e) {
if (e) { e.preventDefault() }

e = $.Event('hide.bs.modal')

this.$element.trigger(e)

if (!this.isShown || e.isDefaultPrevented()) { return }

this.isShown = false

this.escape()

$(document).off('focusin.bs.modal')

this.$element
.removeClass('in')
.attr('aria-hidden', true)
.off('click.dismiss.bs.modal')

$.support.transition && this.$element.hasClass('fade') ?
this.$element
.one($.support.transition.end, $.proxy(this.hideModal, this))
.emulateTransitionEnd(300) :
this.hideModal()
}

Modal.prototype.enforceFocus = function () {
$(document)
.off('focusin.bs.modal') // guard against infinite focus loop
.on('focusin.bs.modal', $.proxy(function (e) {
if (this.$element[0] !== e.target && !this.$element.has(e.target).length) {
this.$element.focus()
}
}, this))
}

Modal.prototype.escape = function () {
if (this.isShown && this.options.keyboard) {
this.$element.on('keyup.dismiss.bs.modal', $.proxy(function (e) {
e.which === 27 && this.hide()
}, this))
} else if (!this.isShown) {
this.$element.off('keyup.dismiss.bs.modal')
}
}

Modal.prototype.hideModal = function () {
var that = this
this.$element.hide()
this.backdrop(function () {
that.removeBackdrop()
that.$element.trigger('hidden.bs.modal')
})
}

Modal.prototype.removeBackdrop = function () {
this.$backdrop && this.$backdrop.remove()
this.$backdrop = null
}

Modal.prototype.backdrop = function (callback) {
var animate = this.$element.hasClass('fade') ? 'fade' : ''

if (this.isShown && this.options.backdrop) {
var doAnimate = $.support.transition && animate

this.$backdrop = $('<div class="modal-backdrop ' + animate + '" />')
.appendTo(document.body)

this.$element.on('click.dismiss.bs.modal', $.proxy(function (e) {
if (e.target !== e.currentTarget) {return}
this.options.backdrop === 'static' ? this.$element[0].focus.call(this.$element[0]) : this.hide.call(this)
}, this))

if (doAnimate) {this.$backdrop[0].offsetWidth} // force reflow

this.$backdrop.addClass('in')

if (!callback) { return }

doAnimate ?
this.$backdrop
.one($.support.transition.end, callback)
.emulateTransitionEnd(150) :
callback()

} else if (!this.isShown && this.$backdrop) {
this.$backdrop.removeClass('in')

$.support.transition && this.$element.hasClass('fade') ?
this.$backdrop
.one($.support.transition.end, callback)
.emulateTransitionEnd(150) :
callback()

} else if (callback) {
callback()
}
}

// MODAL PLUGIN DEFINITION
// =======================

var old = $.fn.modal

$.fn.modal = function (option, _relatedTarget) {
return this.each(function () {
var $this   = $(this)
var data    = $this.data('bs.modal')
var options = $.extend({}, Modal.DEFAULTS, $this.data(), typeof option === 'object' && option)

if (!data) { $this.data('bs.modal', (data = new Modal(this, options))) }
if (typeof option === 'string') { data[option](_relatedTarget) }
else if (options.show) { data.show(_relatedTarget) }
})
}

$.fn.modal.Constructor = Modal

// MODAL NO CONFLICT
// =================

$.fn.modal.noConflict = function () {
$.fn.modal = old
return this
}

// MODAL DATA-API
// ==============

$(document).on('click.bs.modal.data-api', '[data-toggle="modal"]', function (e) {
var $this   = $(this)
var href    = $this.attr('href')
var $target = $($this.attr('data-target') || (href && href.replace(/.*(?=#[^\s]+$)/, ''))) //strip for ie7
var option  = $target.data('bs.modal') ? 'toggle' : $.extend({ remote: !/#/.test(href) && href }, $target.data(), $this.data())

if ($this.is('a')) { e.preventDefault() }

$target
.modal(option, this)
.one('hide', function () {
$this.is(':visible') && $this.focus()
})
})

$(document)
.on('show.bs.modal', '.modal', function () { $(document.body).addClass('modal-open') })
.on('hidden.bs.modal', '.modal', function () { $(document.body).removeClass('modal-open') })

</script>

```

This is how I am invoking the modal 

```
 <button type="button" class="btn" data-toggle="modal" data-target="#myModal">
        Open modal
        </button>

        <!-- The Modal -->
            <div class="modal" id="myModal">
                <div class="modal-dialog">
                    <div class="modal-content">

                <!-- Modal Header -->
                         <div class="modal-header">
                            <h4 class="modal-title">Modal Heading</h4>
                            <button type="button" class="close" data-dismiss="modal">&times;</button>
                        </div>

                    <!-- Modal body -->
                        <div class="modal-body">
                            Modal body..
                        </div>

                    <!-- Modal footer -->
                        <div class="modal-footer">
                            <button type="button" class="btn btn-danger" data-dismiss="modal">Close</button>
                        </div>
                    </div>
                </div>
            </div>

```