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node_modules/es5-ext/function/_define-length.js 1.28 KB
aaac7fed   liuqimichale   add
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  "use strict";
  
  var toPosInt = require("../number/to-pos-integer");
  
  var test = function (arg1, arg2) {
  	return arg2;
  };
  
  var desc, defineProperty, generate, mixin;
  
  try {
  	Object.defineProperty(test, "length", {
  		configurable: true,
  		writable: false,
  		enumerable: false,
  		value: 1
  	});
  } catch (ignore) {}
  
  if (test.length === 1) {
  	// ES6
  	desc = { configurable: true, writable: false, enumerable: false };
  	defineProperty = Object.defineProperty;
  	module.exports = function (fn, length) {
  		length = toPosInt(length);
  		if (fn.length === length) return fn;
  		desc.value = length;
  		return defineProperty(fn, "length", desc);
  	};
  } else {
  	mixin = require("../object/mixin");
  	generate = (function () {
  		var cache = [];
  		return function (length) {
  			var args, i = 0;
  			if (cache[length]) return cache[length];
  			args = [];
  			while (length--) args.push("a" + (++i).toString(36));
  			// eslint-disable-next-line no-new-func
  			return new Function(
  				"fn",
  				"return function (" + args.join(", ") + ") { return fn.apply(this, arguments); };"
  			);
  		};
  	}());
  	module.exports = function (src, length) {
  		var target;
  		length = toPosInt(length);
  		if (src.length === length) return src;
  		target = generate(length)(src);
  		try {
  			mixin(target, src);
  		} catch (ignore) {}
  		return target;
  	};
  }