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Node.js console.time()用法及代码示例


console.time()方法是Node.js的控制台类。它用于启动计时器,该计时器用于计算一段代码或函数所花费的时间。方法console.timeEnd()用于停止计时器并将经过的时间(以毫秒为单位)输出到stdout。计时器可以精确到sub-millisecond。

用法

console.time( label )

参数:此方法接受可以在方法中作为参数传递的单个参数标签,如果未传递标签,则默认标签将自动提供给方法。对于不同的函数或代码段,标签可以不同。


以下示例说明了Node.js中console.time()方法的用法方式:

范例1:

// Node.js program to demonstrate the 
// console.time() method 
  
// Sample function 
function addCount() { 
  // Variable declaration 
  var sum = 0; 
  
  for (var i = 1; i < 100000; i++) { 
    // Adding i to the sum variable 
    sum += i; 
  } 
  
  // Return sum value 
  return sum; 
} 
  
// Starts the timer 
console.time(); 
  
// Function call 
addCount(); 
  
// Ends the timer and print the time 
// taken by the piece of code 
console.timeEnd();

输出:

default:8.760ms

范例2:

// Node.js program to demonstrate the 
// console.time() method 
  
// Sample function 
function addCount() { 
  // Variable declaration 
  var sum = 0; 
  for (var i = 1; i < 100000; i++) { 
    // Adding i to the sum variable 
    sum += i; 
  } 
  return sum; // returning sum 
} 
  
var timetaken = "Time taken by addCount function"; 
  
// Starts the timer. The label value is timetaken 
console.time(timetaken); 
  
addCount(); // function call 
  
// Ends the timer and print the time 
// taken by the piece of code 
console.timeEnd(timetaken);

输出:

Time taken by addCount function:7.380ms

范例3:此示例同时将不同的标签用于不同的函数。

// Node.js program to demonstrate the 
// console.time() method 
  
// Sample function 
function addCount() { 
  var sum = 0; // Variable declaration 
  for (var i = 1; i < 100000; i++) { 
    sum += i; // Adding i to the sum variable 
  } 
  return sum; // returning sum 
} 
  
function countTime() { 
  var timetaken = "Time taken by addCount function"; 
  
  // Starts the timer, the label value is timetaken 
  console.time(timetaken); 
  
  console.log(addCount()); // function call 
  
  // Ends the timer and print the time 
  // taken by the piece of code 
  console.timeEnd(timetaken); 
} 
  
var label2 = "Time taken by countTime function"; 
  
// Starts the timer, the label value is label2 
console.time(label2); 
  
countTime(); // function call 
  
// Ends the timer and print the time 
// taken by the piece of code 
console.timeEnd(label2);

输出:

4999950000
Time taken by addCount function:24.884ms
Time taken by countTime function:25.928ms

参考: https://nodejs.org/docs/latest-v11.x/api/console.html#console_console_time_label



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注:本文由纯净天空筛选整理自akshajjuneja9大神的英文原创作品 Node.js | console.time() Method。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。