html实现下载数据文件

function exportMesh(){
    var string="1 2 3,4";
    var blob=new Blob([string],{type:"text/plain"});
    var a = document.createElement('a');  //创建a标签用于下载
    a.download = 'MeshGrid.txt';
    a.href = URL.createObjectURL(blob);
    document.getElementsByTagName("body")[0].appendChild(a);
    a.click();
    document.getElementsByTagName("body")[0].removeChild(a);
}