动态获取一个元素的位置

在页面中的onclick=a($event)中添加$event可以获取到元素的这些值，
如果我想从其他代码调取点击事件的话，怎么才能也类似这种添加$event呢
例如b() {
a(怎么样设置呢)
}
我试了一下用ID跟ref都不会，请教一个方法。
{
"_processed": true,
"changedTouches": [{
"clientX": 259,
"clientY": 20,
"force": 1,
"identifier": 0,
"pageX": 259,
"pageY": 20
}],
"currentTarget": {
"dataset": {
"id": "menuid3"
},
"id": "",
"offsetLeft": 210,
"offsetTop": 0
},
"detail": {
"x": 259,
"y": 20
},
"mp": {
"@warning": "mp is deprecated",
"changedTouches": [{
"clientX": 259,
"clientY": 20,
"force": 1,
"identifier": 0,
"pageX": 259,
"pageY": 20
}],
"currentTarget": {
"dataset": {
"id": "menuid3"
},
"id": "",
"offsetLeft": 210,
"offsetTop": 0
},
"detail": {
"x": 259,
"y": 20
},
"preventDefault": "function(){}",
"stopPropagation": "function(){}",
"target": {
"dataset": {},
"id": "",
"offsetLeft": 220,
"offsetTop": 10,
"x": 259,
"y": 20
},
"timeStamp": 788671.31499999959,
"touches": [{
"clientX": 259,
"clientY": 20,
"force": 1,
"identifier": 0,
"pageX": 259,
"pageY": 20
}],
"type": "click"
},
"preventDefault": "function(){}",
"stopPropagation": "function(){}",
"target": {
"dataset": {},
"id": "",
"offsetLeft": 220,
"offsetTop": 10,
"x": 259,
"y": 20
},
"timeStamp": 788671.31499999959,
"touches": [{
"clientX": 259,
"clientY": 20,
"force": 1,
"identifier": 0,
"pageX": 259,
"pageY": 20
}],
"type": "click"
}