SOURCE

function replaceHtml(html) {
    let arr = [...html]
    let startList = []
    let endList = []
    arr = arr.map((item, index) => {
        if (item === '>') {
            startList.push(index + 1)
        } if (item === '<') {
            endList.push(index)
        }
        return item
    })
    const arr2 = startList.map((item, index) => {
        return arr.slice(startList[index], endList[index + 1])
    })
    const textList = arr2.reduce((pre, cur, index) => {
        cur = cur.map((item) => {
            return item === ' ' ? '$nbsp;' : item
        })
        const item = {
            idx: index,
            html: cur
        }
        pre.push(item)
        return pre
    }, [])
    let arr3 = arr
    textList.forEach((item, index) => {
        if (item.html.length > 0) {
            for (let i = 0; i < item.html.length; i++) {
                let idx = startList[index] + i
                arr3[idx] = item.html[i]
            }
        }
    })
    const htmlStr = arr3.toString().replace(/,/g, '')
    return `${htmlStr}`
}
const content = `<bode>55<div style=" padding:1px">12   55    3</div></bode>`
const str = replaceHtml(content)
console.log(content);
console.log(str);