[solved] Expected a conditional expression and instead saw an assignment

Reactjs Expected a conditional expression and instead saw an assignment, i can see this warning in the console of my project how can I remove it? the function which cause this error is 

 async deleteCompany(id){
 try{
 let res = await axios.delete(BackendURL+'/save/'+id+'/');
 if(res.status = 200){
 this.props.reload();
 }
 }catch(err){
 console.error(err);
 }
 }

what should I do? 

— Update — 

I found the issue. it's because inside the condition there is one “=”  it supposed to be at least two “==” or three “===”