Refactored, added es5 build

src/Resizer.vue

@@ -0,0 +1,120 @@
+<template>
+  <div :class="className"></div>
+</template>
+<script>
+export default {
+  name: 'Resizer',
+  props: {
+    minHeight: {
+      type: Number,
+      default: 0
+    },
+    minWidth: {
+      type: Number,
+      default: 0
+    }},
+  data() {
+    return {
+      clicked: false,
+      size: {}
+    }
+  },
+  mounted() {
+    this.$el.addEventListener('mousedown', this.start, false)
+  },
+  computed: {
+    className () {
+      return {'vue-modal-resizer': true, 'clicked': this.clicked}
+    }
+  },
+  methods: {
+    start(event) {
+      this.clicked = true
+
+      window.addEventListener('mousemove', this.mousemove, false)
+      window.addEventListener('mouseup', this.stop, false)
+
+      event.stopPropagation()
+      event.preventDefault()
+    },
+    stop() {
+      this.clicked = false
+
+      window.removeEventListener('mousemove', this.mousemove, false)
+      window.removeEventListener('mouseup', this.stop, false)
+
+      this.$emit('resize-stop', {
+        element: this.$el.parentElement,
+        size: this.size
+      });
+    },
+    mousemove(event) {
+      this.resize(event)
+    },
+    resize(event) {
+      var el = this.$el.parentElement
+
+      if (el) {
+        var width = event.clientX - el.offsetLeft
+        var height = event.clientY - el.offsetTop
+
+        if (width < this.minWidth) {
+          width = this.minWidth
+        }
+
+        if (width > window.innerWidth) {
+          width = window.innerWidth
+        }
+
+        if (height < this.minHeight) {
+          height = this.minHeight
+        }
+
+        if (height > window.innerHeight) {
+          height = window.innerHeight
+        }
+
+        this.size = {width, height}
+        el.style.width = width + 'px'
+        el.style.height = height + 'px'
+
+        this.$emit('resize', {
+          element: el,
+          size: this.size
+        })
+      }
+    }
+  }
+}
+</script>
+<style lang="scss">
+.vue-modal-resizer {
+    display: block;
+    overflow: hidden;
+    position: absolute;
+    width: 12px;
+    height: 12px;
+    right: 0;
+    bottom: 0;
+    z-index: 9999999;
+    background: transparent;
+    cursor: se-resize;
+
+    &:after {
+      display: block;
+      position: absolute;
+      content: '';
+      background: transparent;
+      left: 0;
+      top: 0;
+    	width: 0;
+    	height: 0;
+    	border-bottom: 10px solid #ddd;
+    	border-left: 10px solid transparent;
+    }
+
+    &.clicked:after {
+      border-bottom: 10px solid #369BE9;
+    }
+}
+</style>