Here's a no framework code, only pure js :

document.querySelectorAll('img.svg').forEach(function(element) {
            var imgID = element.getAttribute('id')
            var imgClass = element.getAttribute('class')
            var imgURL = element.getAttribute('src')

            xhr = new XMLHttpRequest()
            xhr.onreadystatechange = function() {
                if(xhr.readyState == 4 && (xhr.status == 0 || xhr.status == 200)) {
                    var svg = xhr.responseXML.getElementsByTagName('svg')[0];

                    if(imgID != null) {
                         svg.setAttribute('id', imgID);
                    }

                    if(imgClass != null) {
                         svg.setAttribute('class', imgClass + ' replaced-svg');
                    }

                    svg.removeAttribute('xmlns:a')

                    if(!svg.hasAttribute('viewBox') && svg.hasAttribute('height') && svg.hasAttribute('width')) {
                        svg.setAttribute('viewBox', '0 0 ' + svg.getAttribute('height') + ' ' + svg.getAttribute('width'))
                    }
                    element.parentElement.replaceChild(svg, element)
                }
            }
            xhr.open('GET', imgURL, true)
            xhr.send(null)
        })

Here's a no framework code, only pure js :

document.querySelectorAll('img.svg').forEach(function(element) {
            var imgID = element.getAttribute('id')
            var imgClass = element.getAttribute('class')
            var imgURL = element.getAttribute('src')

            xhr = new XMLHttpRequest()
            xhr.onreadystatechange = function() {
                if(xhr.readyState == 4 && xhr.status == 200) {
                    var svg = xhr.responseXML.getElementsByTagName('svg')[0];

                    if(imgID != null) {
                         svg.setAttribute('id', imgID);
                    }

                    if(imgClass != null) {
                         svg.setAttribute('class', imgClass + ' replaced-svg');
                    }

                    svg.removeAttribute('xmlns:a')

                    if(!svg.hasAttribute('viewBox') && svg.hasAttribute('height') && svg.hasAttribute('width')) {
                        svg.setAttribute('viewBox', '0 0 ' + svg.getAttribute('height') + ' ' + svg.getAttribute('width'))
                    }
                    element.parentElement.replaceChild(svg, element)
                }
            }
            xhr.open('GET', imgURL, true)
            xhr.send(null)
        })

Here's a no framework code, only pure js :

document.querySelectorAll('img.svg').forEach(function(element) {
            var imgID = element.getAttribute('id')
            var imgClass = element.getAttribute('class')
            var imgURL = element.getAttribute('src')

            xhr = new XMLHttpRequest()
            xhr.onreadystatechange = function() {
                if(xhr.readyState == 4 && (xhr.status == 0 || xhr.status == 200)) {
                    var svg = xhr.responseXML.getElementsByTagName('svg')[0];

                    if(typeof imgID !== 'undefined') {
                        svg.setAttribute('id', imgID);
                    }

                    if(typeof imgClass !== 'undefined') {
                        svg.setAttribute('class', imgClass + ' replaced-svg');
                    }

                    svg.removeAttribute('xmlns:a')

                    if(!svg.hasAttribute('viewBox') && svg.hasAttribute('height') && svg.hasAttribute('width')) {
                        svg.setAttribute('viewBox', '0 0 ' + svg.getAttribute('height') + ' ' + svg.getAttribute('width'))
                    }
                    element.parentElement.replaceChild(svg, element)
                }
            }
            xhr.open('GET', imgURL, true)
            xhr.send(null)
        })

Here's a no framework code, only pure js :

document.querySelectorAll('img.svg').forEach(function(element) {
            var imgID = element.getAttribute('id')
            var imgClass = element.getAttribute('class')
            var imgURL = element.getAttribute('src')

            xhr = new XMLHttpRequest()
            xhr.onreadystatechange = function() {
                if(xhr.readyState == 4 && (xhr.status == 0 || xhr.status == 200)) {
                    var svg = xhr.responseXML.getElementsByTagName('svg')[0];

                    if(imgID != null) {
                         svg.setAttribute('id', imgID);
                    }

                    if(imgClass != null) {
                         svg.setAttribute('class', imgClass + ' replaced-svg');
                    }

                    svg.removeAttribute('xmlns:a')

                    if(!svg.hasAttribute('viewBox') && svg.hasAttribute('height') && svg.hasAttribute('width')) {
                        svg.setAttribute('viewBox', '0 0 ' + svg.getAttribute('height') + ' ' + svg.getAttribute('width'))
                    }
                    element.parentElement.replaceChild(svg, element)
                }
            }
            xhr.open('GET', imgURL, true)
            xhr.send(null)
        })