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 问题不在于onload 。 您只是在存在之前访问该属性。 
 
 您永远不会在HomeView构造函数中设置this.el ： 
 
$("body").html(this.el);
this.template = _.template($('#main-template').html());
this.render();
 
 你正在调用this.render() ，它访问this.el.innerHTML ，但在这三行中你设置this.el ？ 无处。 
 
 如果this.el应该由View设置，那么在访问之前你必须调用父构造函数： 
 
constructor() {
    super();
    $("body").html(this.el);
    this.template = _.template($('#main-template').html());

    this.render();
}

The problem is not with onload. You are simply accessing a property before it exists.
 
You are never setting this.el in your HomeView constructor:
 
$("body").html(this.el);
this.template = _.template($('#main-template').html());
this.render();
 
You are calling this.render(), which access this.el.innerHTML, but where in these three lines are you setting this.el? Nowhere.
 
If this.el supposed to be set by View, then you have to call the parent constructor before you access this:
 
constructor() {
    super();
    $("body").html(this.el);
    this.template = _.template($('#main-template').html());

    this.render();
}