Javascript 在for循环javascript中添加数字
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adding numbers in for loop javascript
提问by user1503606
I need to sum all my numbers from a for loop with javascript
我需要用 javascript 从 for 循环中总结我所有的数字
var nums = ['100','300','400','60','40'];
for(var i=1; i < nums.length; i++){
var num = nums[i] + nums[i];
alert(num);
}?
can someone help http://jsfiddle.net/GYpd2/1/
有人可以帮忙http://jsfiddle.net/GYpd2/1/
the outcome i am looking for is 900
我要找的结果是 900
回答by Besnik
var nums = ['100','300','400','60','40'];
var sum = 0;
for(var i=0; i < nums.length; i++){
sum += parseInt(nums[i]);
}
alert(sum);
Tested: http://jsfiddle.net/GYpd2/6/(thanks to user1503606)
测试：http: //jsfiddle.net/GYpd2/6/（感谢user1503606）
If numscontains numbers only there is no need for parseInt().
如果nums只包含数字，则不需要parseInt().
回答by jAndy
Prime example for ES5's Array.prototype.reducemethod. Like:
ES5Array.prototype.reduce方法的主要示例。喜欢：
var nums = ['100','300','400','60','40'];
var total = nums.reduce(function(a,b) {
return (+a)+(+b);
});
回答by Vitalii Petrychuk
var nums = ['100','300','400','60','40'],
num = 0;
for (var i = 0; i < nums.length; i++) {
num += +nums[i];
}
alert(num);
?
回答by aefxx
var num, nums = [100,300,400,60,40];
for ( var i=1; i < nums.length; i++ ) {
num += nums[i];
}?
alert(num);
回答by Subir Kumar Sao
Do it like this
像这样做
var nums = ['100','300','400','60','40'];
var total = 0;
for(var i=0; i < nums.length; i++){
total = total + Number(nums[i]);
}
alert(total);
The loop starts with 0 not 1.
totalvariable needs to be declared before the loop or else it will not preserve the previous addition.Use Number() to convert string to number.
Adding string means concatitation
'100'+'200'will give'100200'.
循环从 0 开始，而不是 1。
total变量需要在循环之前声明，否则它不会保留之前的添加。使用 Number() 将字符串转换为数字。
添加字符串意味着串联
'100'+'200'将给出'100200'.
回答by Scott Sauyet
If you have a reduce function , you can just do this:
如果你有一个reduce 函数，你可以这样做：
var nums = ['100','300','400','60','40'],
sum = nums.reduce(function(accum, val) {return accum + Number(val);}, 0);
alert(sum);
回答by Max Kueng
var i, sum = 0, nums = ['100','300','400','60','40'];
for (i = 0; i < nums.length; i++) {
sum += +nums[i];
}
alet(sum);
You shouldn't use the varstatement inside a loop. Also the parseIntfunction used in other answers will always convert the number to an integer so it wouldn't work with floating point numbers. Prefixing the numbers with +will convert them to a number.
您不应该var在循环内使用该语句。此外parseInt，其他答案中使用的函数将始终将数字转换为整数，因此它不适用于浮点数。将数字作为前缀+会将它们转换为数字。
If you develop for the browser, using the reducefunction might cause problems with older browsers - unless you find a polyfill for it.
如果您为浏览器开发，使用该reduce功能可能会导致旧浏览器出现问题 - 除非您为它找到了 polyfill。
回答by user201827
var nums = ['100','300','400','60','40'];
var num = 0;
for(var i=0; i < nums.length; i++){
num = parseInt(num) + parseInt(nums[i]);
}
This is how I did it. It's very similar to other's code, but a different way of writing it. You do need to start your initial i value in your for loop with 0.
我就是这样做的。它与其他人的代码非常相似，但编写方式不同。您确实需要在 for 循环中以 0 开始初始 i 值。
回答by Matthew Layton
Here's an example that uses an extension of the Number prototype, similar to LINQ's sum method:
这是一个使用 Number 原型扩展的示例，类似于 LINQ 的 sum 方法：
Array.prototype.sum = function () {
var result = 0;
this.forEach(function (o) { result += Number(o); });
return result;
};
var sum = ['100','300','400','60','40'].sum();
回答by SuperNova
You can do something like this..
你可以做这样的事情..
var nums = ['100','300','400','60','40'];
nums.reduceRight(function(a,b){return Number(a)+Number(b);})
