为什么我使用jQuery获取[object object]？

Question

I have a function there i want to try sum two numbers using variable like given below, but i'm getting [object object] instead of total of sum.

 var convenienceCharge = 100; var totalPgCost = 500; var subTotalPgCost = 0; function totalPgCostFunction() { subTotalPgCost += $('.subTotalPgCost').text(convenienceCharge + totalPgCost + 18); alert(subTotalPgCost); } 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <button onclick="totalPgCostFunction();">Click</button> 

Answer 1

.text will return a object. that is why you are seeing [object object]

You need to do it like this.

 var convenienceCharge = 100; var totalPgCost = 500; var subTotalPgCost = 0; function totalPgCostFunction() { subTotalPgCost += convenienceCharge + totalPgCost + 18; $('.subTotalPgCost').text(subTotalPgCost); alert(subTotalPgCost); } 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <button onclick="totalPgCostFunction();">Click</button> <div class="subTotalPgCost"></div> 

Answer 2

The issue is because when you call the setter of text() it returns a jQuery object, hence the output you see.

To make this work you need to split the calculation and text() logic, like this:

 var convenienceCharge = 100; var totalPgCost = 500; var subTotalPgCost = 0; $(function() { $('button').click(function() { subTotalPgCost += convenienceCharge + totalPgCost + 18; $('.subTotalPgCost').text(subTotalPgCost); }); }); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <button>Click</button> <div class="subTotalPgCost"></div> 

Also note the use of an unobtrusive event handler in this example instead of the outdated on* attribute.