<p>I have a very strange js problem. I have a Vue component (but I don't think Vue is important here). It has a data attribute called <code>current_query</code>. In the method that responds to the event, I want to modify the property. Use Lodash here. There is a very strange behavior. Assume <code>this.current_query</code> is initially equal to <code>{ test: 500 }</code>. Assume that the <code>'field'</code> parameter is <code>'test'</code>. By "unsetting" it from <code>current_query</code>, I will actually clear current_query itself. very good. The problem is, only when using unset, if I log the current_query before calling unset, I get an empty object. How can this be? </p> <pre class="brush:php;toolbar:false;">on_applied_option_click(field){ console.log(this.current_query); // gives { test: 500 } (OK) }, // Click to end on_applied_option_click(field){ console.log(this.current_query); // Only when using _.unset will an empty object be given (??) _.unset(this.current_query, field); console.log(this.current_query); // Will also give an empty object (OK) }, // Click to end</pre> <p>I found that if I use <code>_.omit</code>, everything works fine: </p> <pre class="brush:php;toolbar:false;">on_applied_option_click(field){ console.log(this.current_query); // gives { test: 500 } (OK) this.current_query = _.omit(this.current_query, field); console.log(this.current_query); // Give an empty object, which is OK at this time }, // Click to end</pre> <p>Why? The only thing I can say is that _.unset changes the object while _.omit creates new objects. However, I don't think it's possible for _.unset to change the object before calling it (???). Never seen anything like this. Does anyone have a good explanation for this strange behavior? </p>