Created
May 26, 2016 14:08
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Limit number of function running at the same time
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta name="description" content="Call any function just once within a period of time"> | |
| <meta charset="utf-8"> | |
| <meta name="viewport" content="width=device-width"> | |
| <title>JS Bin</title> | |
| </head> | |
| <body> | |
| <input type="button" value="Call function 3 times" onclick="onClick()"> | |
| </body> | |
| </html> |
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| var period = 1000; | |
| var n = 2; //max number of functions executiong within a period | |
| //function decorator | |
| function getFunction(context){ | |
| return function(func){ | |
| var running = 0; | |
| return function(){ | |
| if (running === n){ | |
| console.log(running + " functions are running. Only " + n + " functions can run at the same time. Cancel excecution"); | |
| return; | |
| } | |
| running++; | |
| func.apply(context, arguments); | |
| setTimeout(function(){ | |
| running--; | |
| }, period); | |
| }; | |
| }; | |
| } | |
| //function that takes much time | |
| function getData(filter, callback){ | |
| console.log("Call function with argument filter = " + filter); | |
| setTimeout(function(){ | |
| callback(null, {data: [1, 2, 3]}); | |
| }, 500); | |
| } | |
| //create a wrapper | |
| var wrapper = getFunction(this)(getData); | |
| //call this function 3 times when button is clicked | |
| function onClick(){ | |
| var filter = "some filter"; | |
| var callback = function(err, result){ | |
| if (err){ | |
| console.log("Error: " + err); | |
| return; | |
| } | |
| console.log("Function is complete. Result = " + JSON.stringify(result)); | |
| }; | |
| wrapper(filter, callback); | |
| wrapper(filter, callback); | |
| wrapper(filter, callback); | |
| } |
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