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://*.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
}