cannot get variable value

[keat]

Hi, i want to pass value from the HTML element to the type script variable , but when i write this.ShowMs(show), it show error of "Property 'ShowMs' does not exist  on type 'HTMLElement'. Anyone know what i missing? Below is the code.

ping():void{

var intStartTime;

intStartTime = +new Date();

var objIMG = new Image();

var show;

 

objIMG.src = this.url + "/" + intStartTime ;

 

objIMG.onload =

objIMG.onerror =

function()

{

 

var delay = Number(new Date()) - Number(intStartTime);

 

show = (delay<1)?("<1"):(" = "+delay);

 

console.log( " Ping" + show + " ms");

 

this.ShowMs(show);

}

 

 

}

 

ShowMs(passData:any):void{

 

if(passData < 100){

this.txt.color = "#3FFF00";

this.txt.text = passData;

}else if(passData < 300){

this.txt.color = "#C5FF0D";

this.txt.text = passData;

}else if(passData > 300){

this.txt.color = "#FF0000";

this.txt.text = passData;

}else{

this.txt.color = "#FF0000";

this.txt.text = passData;

}

}