SOURCE

class showFewRows {
    constructor (el, options = {}) {
        this.options = Object.assign({
            content: '',
            btnHTML: '展开',
            lineHeight: 1.5,
            fontSize: '16px',
            rows: 3
        }, options)
        this.el = document.createElement('div')
        this.textarea = document.createElement('textarea')
        this.textarea.innerHTML = content
    }
}