/*** 等比缩放* @param wrap 外部容器* @param container 待缩放的容器* @returns {{width: number, height: number}}* 返回值：width:宽度, height:高度*/aspectRatio(wrap: any, container: any) {// w = h / ratio, h = w * ratioconst wrapW = wrap.width;const wrapH = wrap.height;let cW = container.width;let cH = container.height;const rc = cW / cH;if (rc > 1) {// const w = wrapH * ratio;if (cW <= wrapW) {cW = wrapW;cH = wrapW / rc;}} else if (rc < 1) { // w:h = w1:h1 =>if (cH <= wrapH) {cH = wrapH;cW = rc * cH;}} else if (rc === 1) {const v = wrapW > wrapH ? wrapH : wrapW;cH = v;cW = v;}return {width: cW,height: cH,};}

原文链接

JavaScript元素根据父级元素宽高缩放