1.textarea高度自适应
这个非常有用，但是网上的解决方案都不尽人意，话不多说，上代码。
function auto (elem) { ?var minHeight = 30 ?var change = function () { ????elem.style.height = minHeight + ‘px‘ ????elem.style.overflowY = ‘hidden‘ ????if (elem.scrollHeight > minHeight) { ?????????????elem.style.height = elem.scrollHeight + ‘px‘ ????} ?} ?elem.addEventListener("input", change, false) ?elem.addEventListener("focus", change, false) ?elem.addEventListener("propertychange", change, false) ?change()}思路很简单，根据内容高度不断重置textarea高度，绑定input, focus, propertychange事件
2.自动计算Y轴高度，先放算法参考链接：https://stackoverflow.com/questions/326679/choosing-an-attractive-linear-scale-for-a-graphs-y-axis
意思就是给定几个数值，要能在y轴上较好的展示（算出上下限和区间值）
function scaleNumber (max, min, i) { ?let unround = (max - min) / i ??// 等分刻度 ?let x = Math.ceil(Math.log10(unround)) ?let pow10x = Math.pow(10, x) ?let arr = [0.1, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 1] ?for (let item of arr) { ???if (unround / pow10x <= item) { ?????var range = item * pow10x ?????break ???} ?} ?console.log(range) ?min = range * Math.floor(min / range) ?max = range * Math.ceil(max / range) ?return [max, min]}参数i表示需要分几段
3.json转table,这个比较简单但是也比较实用，就记录下来：
???function json2html (str) { ?????var reg = /\[{2}((?!\]\]).)+\]{2}/g ?????var jsonstrarr = [] ?????var htmlstrarr = [] ?????var result ?????while((result = reg.exec(str)) !== null) { ???????// console.log(result) ???????jsonstrarr.push(result[0]) ?????} ?????console.log(jsonstrarr) ?????for (let item of jsonstrarr) { ???????let obj = JSON.parse(item) ???????let htmlstr = `<table cellpadding="0" border="1">` ???????for (let i of obj) { ?????????htmlstr += ‘<tr>‘ ?????????for (let j of i) { ???????????htmlstr += `<td colspan="${j.col}" rowspan="${j.row}">${j.value}</td>` ?????????} ?????????htmlstr += ‘</tr>‘ ???????} ???????htmlstr += ‘</table>‘ ???????htmlstrarr.push(htmlstr) ?????} ?????let newstr = str ?????for (let index in jsonstrarr) { ???????newstr = newstr.replace(jsonstrarr[index], htmlstrarr[index]) ?????} ?????return newstr ???}实用小工具不定期合集(textarea 高度自适应、自动计算Y轴刻度、json转table)
原文地址：https://www.cnblogs.com/CheapTrick/p/9688381.html