interface LogEntry {
data: any
time: Date
}
export class PersistantLog {
//最大条数
maxEntries = 3000;
isEnabled = false;
name = "default_log";
localStorage = window.localStorage;
entries: LogEntry[] = JSON.parse(this.localStorage.getItem(this.name));
constructor() {
this.isEnabled = true;
}
public log(info: any) {
if (!this.isEnabled) return;
this.entries.push({
time: new Date(),
data: info
})
this.save();
}
public enable() {
this.isEnabled = true;
}
private save() {
this.entries = this.entries.slice(-this.maxEntries)
let data = JSON.stringify(this.entries)
this.localStorage.setItem(this.name, data)
}
public clear() {
this.localStorage.removeItem(this.name);
}
private getEntries() {
return this.entries
}
public exportLog(exportFileName: string) {
let resultStr = this.localStorage.getItem(this.name)
//将文本或者JS字符串信息借助Blob转换成二进制，然后，
//作为<a>元素的href属性，配合download属性，实现下载
if ("download" in document.createElement("a")) {
let eleLink = document.createElement("a")
eleLink.download = exportFileName + ".json"
eleLink.style.display = "none"
let blob = new Blob([resultStr])
eleLink.href = URL.createObjectURL(blob)
//兼容firefox,元素添加到页面才能触发点击
document.body.appendChild(eleLink)
eleLink.click()
document.body.removeChild(eleLink)
}
}
}