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字符串转数组split() 函数和数组转字符串join() 函数实例

var string="abcdefg"
console.log(string.split(''));
// 输出结果：["a", "b", "c", "d", "e", "f", "g"]

var array=["a", "b", "c", "d", "e", "f", "g"];
console.log(array.join(','));
// 输出结果：a,b,c,d,e,f,g

JavaScript toFixed() 方法可把Number值四舍五入为指定小数位数的数字。

function format(point) {
  var num = new Number(point);
  return num.toFixed(3)
}
console.log(format('2.236834234'))
// 输出结果 2.237

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